Synaptobrevins, also known as VAMPs, along with syntaxins and the synaptosomal-associated protein SNAP25, form the protein complex that is involved with the docking and fusion of synaptic vesicles with the presynaptic membrane. Synaptobrevins have a molecular weight of 18 kD, and are also involved in the formation of the SNARE complexes. The synaptobrevins are degraded by the protein tetanospasmin, from the tetanus-causing bacterium Clostridium tetani, as well as botulinum toxin from Clostridium botulinum.

SMI 71 is specific for a rat endothelial protein found in areas with blood-brain or blood-nerve barriers. The antibody does not react with endothelia of periventricular organs or with fenestrated endothelia in peripheral tissues. Specifically, it has been shown that staining with SMI 71 is not observed in blood vessels and sinusoids in the liver, vessels in the heart, adrenal, skeletal muscle, intestine, thymus, lymph nodes, pancreas, thyroid, or skin. However, a patchy reaction was observed on some vessel walls of the spleen and epidermis of the skin3. Reactivity with the antibody develops in newborn rats along with maturation of the blood brain barrier. Reactivity disappears in lesions of experimental allergic encephalomyelitis. Contrary to the belief that astrocytes and perhaps neurons are essential for the establishment of the blood-brain barrier, destruction of neurons (monitored by SMI 311 and anti-MAP2) and of astrocytes (monitored by anti-GFAP and anti-S100B) leads only to transient abolition of SMI 71 reactivity and only transient transendothelial passage of serum albumin.

SMI 71 is specific for a rat endothelial protein found in areas with blood-brain or blood-nerve barriers. The antibody does not react with endothelia of periventricular organs or with fenestrated endothelia in peripheral tissues. Specifically, it has been shown that staining with SMI 71 is not observed in blood vessels and sinusoids in the liver, vessels in the heart, adrenal, skeletal muscle, intestine, thymus, lymph nodes, pancreas, thyroid, or skin. However, a patchy reaction was observed on some vessel walls of the spleen and epidermis of the skin3. Reactivity with the antibody develops in newborn rats along with maturation of the blood brain barrier. Reactivity disappears in lesions of experimental allergic encephalomyelitis. Contrary to the belief that astrocytes and perhaps neurons are essential for the establishment of the blood-brain barrier, destruction of neurons (monitored by SMI 311 and anti-MAP2) and of astrocytes (monitored by anti-GFAP and anti-S100B) leads only to transient abolition of SMI 71 reactivity and only transient transendothelial passage of serum albumin.

Myelin basic protein (MBP) is a protein involved in the myelination of nerves in the central nervous system (CNS). MBP functions to maintain the correct structure of myelin, through its interaction with the lipids in the myelin membrane. The myelin sheath is made up of MBP and lipids, and acts as an insulator to increase the velocity of axonal impulse conduction. MBP plays a central role in the demyelinating disease multiple sclerosis (MS). A hallmark of the disease is the loss of the myelin sheath surrounding nerves, thought to be induced by antibodies against MBP.

High CNPase expression is seen in myelin producing cells, including oligodendrocytes and Schwann cells. CNPase accounts for roughly 4% of the total myelin protein in the central nervous system (CNS). CNPase binds to tubulin heterodimers and plays a role in tubulin polymerization, and oligodendrocyte process outgrowth. The enzyme isolated from the mammalian brain is primarily a mixed dimer of approximately 94 kD. The dimer consists of a varied proportion of CNP1 (46 kD) and CNP2 (48 kD) subunits in various species. Since the enzyme is a myelin-associated enzyme, it is of considerable interest in the study of diseases and disorders in which myelin is affected, such as multiple sclerosis, subacute sclerosing panencephalitis, acquired immunodeficiency with CNS involvement, and peripheral neuropathies. The combination of clone SMI 91 with clone SMI 94 and/or clone SMI 99 is useful for immunocytochemical studies on the progression of normal and pathologic myelination.

High CNPase expression is seen in myelin producing cells, including oligodendrocytes and Schwann cells. CNPase accounts for roughly 4% of the total myelin protein in the central nervous system (CNS). CNPase binds to tubulin heterodimers and plays a role in tubulin polymerization, and oligodendrocyte process outgrowth. The enzyme isolated from the mammalian brain is primarily a mixed dimer of approximately 94 kD. The dimer consists of a varied proportion of CNP1 (46 kD) and CNP2 (48 kD) subunits in various species. Since the enzyme is a myelin-associated enzyme, it is of considerable interest in the study of diseases and disorders in which myelin is affected, such as multiple sclerosis, subacute sclerosing panencephalitis, acquired immunodeficiency with CNS involvement, and peripheral neuropathies. The combination of clone SMI 91 with clone SMI 94 and/or clone SMI 99 is useful for immunocytochemical studies on the progression of normal and pathologic myelination.

High CNPase expression is seen in myelin producing cells, including oligodendrocytes and Schwann cells. CNPase accounts for roughly 4% of the total myelin protein in the central nervous system (CNS). CNPase binds to tubulin heterodimers and plays a role in tubulin polymerization, and oligodendrocyte process outgrowth. The enzyme isolated from the mammalian brain is primarily a mixed dimer of approximately 94 kD. The dimer consists of a varied proportion of CNP1 (46 kD) and CNP2 (48 kD) subunits in various species. Since the enzyme is a myelin-associated enzyme, it is of considerable interest in the study of diseases and disorders in which myelin is affected, such as multiple sclerosis, subacute sclerosing panencephalitis, acquired immunodeficiency with CNS involvement, and peripheral neuropathies. The combination of clone SMI 91 with clone SMI 94 and/or clone SMI 99 is useful for immunocytochemical studies on the progression of normal and pathologic myelination.

Synaptosomal-associated protein 25 (SNAP-25) is a component of the trans-SNARE (t-SNARE) complex. SNAP-25 has been reported to account for the specificity of membrane fusion, and to directly execute fusion by forming a tight complex that brings the synaptic vesicle and plasma membranes together. SNAP-25 has been shown to inhibits both ATP-dependent and independent Ca2+-triggered release of glutamate from central nervous system (CNS) synaptosomal membranes. This indicates that SNAP-25 has a role not only in the formation of the synaptic vesicle-target v- and t-SNARE complex, but also in the final neurotransmitter release.

Synaptosomal-associated protein 25 (SNAP-25) is a component of the trans-SNARE (t-SNARE) complex. SNAP-25 has been reported to account for the specificity of membrane fusion, and to directly execute fusion by forming a tight complex that brings the synaptic vesicle and plasma membranes together. SNAP-25 has been shown to inhibits both ATP-dependent and independent Ca2+-triggered release of glutamate from central nervous system (CNS) synaptosomal membranes. This indicates that SNAP-25 has a role not only in the formation of the synaptic vesicle-target v- and t-SNARE complex, but also in the final neurotransmitter release.

Neurofilaments (NF) are ~10 nanometer intermediate filaments found in neurons. They are a major component of the neuronal cytoskeleton, and function primarily to provide structural support for the axon and regulate axon diameter. Neurofilaments belong to the same protein family as the intermediate filaments of other tissues such as keratins, which make the filaments expressed in epithelia. The family of proteins that includes the intermediate filaments is divided into 5 major classes, the keratins forming the classes I and II. Class III contains the proteins vimentin, desmin, peripherin and glial fibrillary acidic protein (GFAP). The major neurofilament subunits occupy the class IV family of intermediate filaments, along with two other filament proteins of neurons, alpha-internexin and nestin. The class IV intermediate filament genes share two unique introns not found in other intermediate filament gene sequences. Finally, class V corresponds to intermediate filaments of the nuclear cytoskeleton, the nuclear lamins. Neurofibrils are bundles of neurofilaments.

There are three major neurofilament subunits, and the names given to these subunits are based upon the apparent molecular mass of the mammalian subunits on SDS-PAGE: The light or lowest (NF-L) runs at 68-70 kD. The medium or middle (NF-M) runs at about 145-160 kD. The heavy or highest (NF-H) runs at 200-220 kD.

These three proteins are referred to as the "neurofilament triplet”. Antibodies against neurofilaments are useful for identification of neurons and their processes in histological sections and in tissue culture. The true molecular masses of these proteins are considerably lower than estimated based on SDS-PAGE mobility, particularly in the case of NF-H and NF-M. This is due to the highly charged C-terminal regions of the molecules. All three triplet proteins contain long stretches of polypeptide sequence rich in glutamic acid residues, and NF-M and especially NF-H also contain multiple tandemly repeated serine phosphorylation sites. These sites contain the peptide sequence lysine-serine-proline, and phosphorylation is predominantly found on axonal and not dendritic neurofilaments. Human NF-M has 13 of these KSP sites, while human NF-H is expressed from two alleles one of which produces 44 and the other 45 KSP repeats.

The fourth class IV subunit, alpha-internexin (NF66) was discovered much later than NF-L, NF-M and NF-H, and is found co-polymerized with these proteins in most mature neurons. The fifth protein belonging to class IV, Nestin, is found in developing neurons and glia, and the presence of this protein is widely used to define neurogenesis. This protein is lost as development proceeds.

The class III intermediate filament protein subunit peripherin is found in neurofilaments along with the class IV subunits in a few neurons, mostly in the peripheral nervous system. Finally another class III intermediate filament subunit, vimentin, is found in developing neurons and a few very unusual neurons in the adult in association with class IV proteins, such as the horizontal neurons of the retina.

In the adult mammal neurofilament subunit proteins coassemble , forming a heteropolymer that contain NF-L or alpha-internexin plus NF-M or NF-H. Peripherin and vimentin may incorporate into neurofilaments along with these proteins. The NF-H and NF-M proteins have lengthy C-terminal tail domains that appear to control the spacing between neighboring filaments, generating aligned arrays with a fairly uniform interfilament spacing as seen in axons.

During axonal growth, new neurofilament subunits are incorporated all along the axon in a dynamic process that involves the addition of subunits along the filament length, as well as the addition of subunits at filament ends. The level of neurofilament gene expression correlates with axonal diameter, which controls how fast electrical signals travel down the axon. Mutant mice with neurofilament abnormalities have phenotypes resembling amyotrophic lateral sclerosis. Neurofilament, NF, immunostaining is common in diagnostic neuropathology. It is useful for differentiating neurons (positive for NF) from glia (negative for NF).

Neurofilaments (NF) are ~10 nanometer intermediate filaments found in neurons. They are a major component of the neuronal cytoskeleton, and function primarily to provide structural support for the axon and regulate axon diameter. Neurofilaments belong to the same protein family as the intermediate filaments of other tissues such as keratins, which make the filaments expressed in epithelia. The family of proteins that includes the intermediate filaments is divided into 5 major classes, the keratins forming the classes I and II. Class III contains the proteins vimentin, desmin, peripherin and glial fibrillary acidic protein (GFAP). The major neurofilament subunits occupy the class IV family of intermediate filaments, along with two other filament proteins of neurons, alpha-internexin and nestin. The class IV intermediate filament genes share two unique introns not found in other intermediate filament gene sequences. Finally, class V corresponds to intermediate filaments of the nuclear cytoskeleton, the nuclear lamins. Neurofibrils are bundles of neurofilaments.

There are three major neurofilament subunits, and the names given to these subunits are based upon the apparent molecular mass of the mammalian subunits on SDS-PAGE: The light or lowest (NF-L) runs at 68-70 kD. The medium or middle (NF-M) runs at about 145-160 kD. The heavy or highest (NF-H) runs at 200-220 kD.

These three proteins are referred to as the "neurofilament triplet”. Antibodies against neurofilaments are useful for identification of neurons and their processes in histological sections and in tissue culture. The true molecular masses of these proteins are considerably lower than estimated based on SDS-PAGE mobility, particularly in the case of NF-H and NF-M. This is due to the highly charged C-terminal regions of the molecules. All three triplet proteins contain long stretches of polypeptide sequence rich in glutamic acid residues, and NF-M and especially NF-H also contain multiple tandemly repeated serine phosphorylation sites. These sites contain the peptide sequence lysine-serine-proline, and phosphorylation is predominantly found on axonal and not dendritic neurofilaments. Human NF-M has 13 of these KSP sites, while human NF-H is expressed from two alleles one of which produces 44 and the other 45 KSP repeats.

The fourth class IV subunit, alpha-internexin (NF66) was discovered much later than NF-L, NF-M and NF-H, and is found co-polymerized with these proteins in most mature neurons. The fifth protein belonging to class IV, Nestin, is found in developing neurons and glia, and the presence of this protein is widely used to define neurogenesis. This protein is lost as development proceeds.

The class III intermediate filament protein subunit peripherin is found in neurofilaments along with the class IV subunits in a few neurons, mostly in the peripheral nervous system. Finally another class III intermediate filament subunit, vimentin, is found in developing neurons and a few very unusual neurons in the adult in association with class IV proteins, such as the horizontal neurons of the retina.

In the adult mammal neurofilament subunit proteins coassemble , forming a heteropolymer that contain NF-L or alpha-internexin plus NF-M or NF-H. Peripherin and vimentin may incorporate into neurofilaments along with these proteins. The NF-H and NF-M proteins have lengthy C-terminal tail domains that appear to control the spacing between neighboring filaments, generating aligned arrays with a fairly uniform interfilament spacing as seen in axons.

During axonal growth, new neurofilament subunits are incorporated all along the axon in a dynamic process that involves the addition of subunits along the filament length, as well as the addition of subunits at filament ends. The level of neurofilament gene expression correlates with axonal diameter, which controls how fast electrical signals travel down the axon. Mutant mice with neurofilament abnormalities have phenotypes resembling amyotrophic lateral sclerosis. Neurofilament, NF, immunostaining is common in diagnostic neuropathology. It is useful for differentiating neurons (positive for NF) from glia (negative for NF).

Neurofilaments (NFs) are ~10 nanometer, type IV intermediate filaments expressed in neurons. NFs are the major components of the neuronal cytoskeleton, and primarily function to provide structural support for axons and regulate axonal diameter. There are three major mammalian neurofilament subunits, which are named based on their apparent molecular weight: 1) neurofilament light (NF-L, ~70 kD), 2) neurofilament medium (NF-M, ~145-160 kD), and 3) neurofilament heavy (NF-H, ~200-220 kD). Neurofilaments are extensively phosphorylated, and their phosphorylation status plays an important role in modulation of their function. Abnormal NF modifications, mutations, and accumulation have been associated with neurodegenerative diseases. NF immunostaining is commonly used as a diagnostic marker for neuropathology detection. NFs are also useful for differentiating neurons (positive for NF) from glia (negative for NF).

Neurofilaments (NF) are approximately 10 nanometer intermediate filaments found in neurons. They are a major component of the neuronal cytoskeleton, and function primarily to provide structural support for the axon and to regulate the axon diameter. There are three major NF subunits, and the names given to these subunits are based upon the apparent molecular mass of the mammalian subunits on SDS-PAGE. The light or lowest NF (NF-L) runs at 68-70 kD. The medium or middle NF (NF-M) runs at about 145-160 kD, and the heavy or highest NF (NF-H) runs at 200-220 kD. However, the actual molecular weight of these proteins is considerably lower due to the highly charged C-terminal regions of the molecules. The level of NF gene expression correlates with the axonal diameter, which controls how fast electrical signals travel down the axon. Mutant mice with NF abnormalities have phenotypes resembling amyotrophic lateral sclerosis. NF immunostaining is common in diagnostic neuropathology. It is useful for differentiating neurons (positive for NF) from the glia (negative for NF).

Neurofilaments (NF) are approximately 10 nanometer intermediate filaments found in neurons. They are a major component of the neuronal cytoskeleton, and function primarily to provide structural support for the axon and to regulate the axon diameter. There are three major NF subunits, and the names given to these subunits are based upon the apparent molecular mass of the mammalian subunits on SDS-PAGE. The light or lowest NF (NF-L) runs at 68-70 kD. The medium or middle NF (NF-M) runs at about 145-160 kD, and the heavy or highest NF (NF-H) runs at 200-220 kD. However, the actual molecular weight of these proteins is considerably lower due to the highly charged C-terminal regions of the molecules. The level of NF gene expression correlates with the axonal diameter, which controls how fast electrical signals travel down the axon. Mutant mice with NF abnormalities have phenotypes resembling amyotrophic lateral sclerosis. NF immunostaining is common in diagnostic neuropathology. It is useful for differentiating neurons (positive for NF) from the glia (negative for NF).

Neurofilaments (NFs) are approximately 10 nanometer intermediate filaments found in neurons. They are a major component of the neuronal cytoskeleton, and function primarily to provide structural support for the axon and to regulate the axon diameter. There are three major NF subunits, and the names given to these subunits are based upon the apparent molecular mass of the mammalian subunits on SDS-PAGE. The light or lowest neurofilament (NF-L) runs at 68-70 kD. The medium or middle (NF-M) runs at about 145-160 kD, and the heavy or highest (NF-H) runs at 200-220 kD. However, the actual molecular weight of these proteins is considerably lower due to the highly charged C-terminal regions of the molecules. The level of NF gene expression correlates with the axonal diameter, which controls how fast electrical signals travel down the axon. Mutant mice with NF abnormalities have phenotypes resembling amyotrophic lateral sclerosis. NF immunostaining is common in diagnostic neuropathology. It is useful for differentiating neurons (positive for NF) from the glia (negative for NF).

Neurofilaments (NF) are approximately 10 nanometer intermediate filaments found in neurons. They are a major component of the neuronal cytoskeleton, and function primarily to provide structural support for the axon and to regulate the axon diameter. There are three major NF subunits, and the names given to these subunits are based upon the apparent molecular mass of the mammalian subunits on SDS-PAGE. The light or lowest NF (NF-L) runs at 68-70 kD. The medium or middle NF (NF-M) runs at about 145-160 kD, and the heavy or highest NF (NF-H) runs at 200-220 kD. However, the actual molecular weight of these proteins is considerably lower due to the highly charged C-terminal regions of the molecules. The level of NF gene expression correlates with the axonal diameter, which controls how fast electrical signals travel down the axon. Mutant mice with NF abnormalities have phenotypes resembling amyotrophic lateral sclerosis. NF immunostaining is common in diagnostic neuropathology. It is useful for differentiating neurons (positive for NF) from the glia (negative for NF).

Neurofilaments (NF) are approximately 10 nanometer intermediate filaments found in neurons. They are a major component of the neuronal cytoskeleton, and function primarily to provide structural support for the axon and to regulate the axon diameter. There are three major NF subunits, and the names given to these subunits are based upon the apparent molecular mass of the mammalian subunits on SDS-PAGE. The light or lowest NF (NF-L) runs at 68-70 kD. The medium or middle NF (NF-M) runs at about 145-160 kD, and the heavy or highest NF (NF-H) runs at 200-220 kD. However, the actual molecular weight of these proteins is considerably lower due to the highly charged C-terminal regions of the molecules. The level of NF gene expression correlates with the axonal diameter, which controls how fast electrical signals travel down the axon. Mutant mice with NF abnormalities have phenotypes resembling amyotrophic lateral sclerosis. NF immunostaining is common in diagnostic neuropathology. It is useful for differentiating neurons (positive for NF) from the glia (negative for NF).

Glial fibrillary acidic protein (GFAP) is an intermediate filament (IF) protein that is expressed by numerous cell types of the central nervous system (CNS) including astrocytes and ependymal cells. GFAP has also been found to be expressed in glomeruli and peritubular fibroblasts, Leydig cells of the testis, keratinocytes, osteocytes and chondrocytes and stellate cells of the pancreas and liver. GFAP is a type III IF protein that is closely related to its non-epithelial family members, vimentin, desmin, and peripherin, which are all involved in the structure and function of the cell’s cytoskeleton. GFAP is thought to help to maintain astrocyte mechanical strength, as well as the shape of cells.

Type III intermediate filaments are highly conserved and contain three domains, named the head, rod and tail domains. This rod domain coils around that of another filament to form a dimer, with the N-terminal and C-terminal of each filament aligned. Type III filaments such as GFAP are capable of forming both homodimers and heterodimers; GFAP can polymerize with other type III proteins or with neurofilament light chain protein (NF-L). Interestingly, GFAP and other type III IF proteins cannot assemble with keratins, the type I and II intermediate filaments: in cells that express both proteins, two separate intermediate filament networks form.

To form networks, the initial GFAP dimers combine to make staggered tetramers, which are the basic subunits of an intermediate filament. The non-helical head and tail domains are necessary for filament formation. The head and tail regions have greater variability of sequence and structure. In spite of this increased variability, the head of GFAP contains two conserved arginines and an aromatic residue that are required for proper assembly.

Glial fibrillary acidic protein (GFAP) is an intermediate filament (IF) protein that is expressed by numerous cell types of the central nervous system (CNS) including astrocytes and ependymal cells. GFAP has also been found to be expressed in glomeruli and peritubular fibroblasts, Leydig cells of the testis, keratinocytes, osteocytes and chondrocytes and stellate cells of the pancreas and liver. GFAP is a type III IF protein that is closely related to its non-epithelial family members, vimentin, desmin, and peripherin, which are all involved in the structure and function of the cell’s cytoskeleton. GFAP is thought to help to maintain astrocyte mechanical strength, as well as the shape of cells.

Type III intermediate filaments are highly conserved and contain three domains, named the head, rod and tail domains. This rod domain coils around that of another filament to form a dimer, with the N-terminal and C-terminal of each filament aligned. Type III filaments such as GFAP are capable of forming both homodimers and heterodimers; GFAP can polymerize with other type III proteins or with neurofilament light chain protein (NF-L). Interestingly, GFAP and other type III IF proteins cannot assemble with keratins, the type I and II intermediate filaments: in cells that express both proteins, two separate intermediate filament networks form.

To form networks, the initial GFAP dimers combine to make staggered tetramers, which are the basic subunits of an intermediate filament. The non-helical head and tail domains are necessary for filament formation. The head and tail regions have greater variability of sequence and structure. In spite of this increased variability, the head of GFAP contains two conserved arginines and an aromatic residue that are required for proper assembly.

Tau protein promotes microtubule assembly and stability. Tau is abundant in neurons of the central nervous system, and is expressed at low levels in astrocytes and oligodendrocytes. Abnormal hyper-phosphorylation, aggregation, and toxic gain of function of tau is associated with several neurological disorders, including Alzheimer’s disease (AD). The major building block of neurofibrillary lesions in AD brains consists of paired helical filaments (PHFs) of abnormally hyperphosphorylated tau. Six isoforms of tau are generated by alternative splicing of the MAPT gene. These isoforms are distinguished by the number of tubulin binding domains, 3 (3R) or 4 (4R), in the C-terminal of the protein and by one (1N), two (2N), or no (0N) inserts in the N-terminal domain.  Tau isoforms are differentially expressed during development.