Synaptosomal-associated protein 23 is a protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 that in humans is encoded by the SNAP23 gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

. Two alternative transcript variants encoding different protein isoforms have been described for this gene.

Function

Specificity of vesicular transport is regulated, in part, by the interaction of a vesicle-associated membrane protein termed synaptobrevin

Synaptobrevin

Synaptobrevins are small integral membrane proteins of secretory vesicles with molecular weight of 18 kilodalton that are part of the vesicle-associated membrane protein family....

/VAMP with a target compartment membrane protein termed syntaxin

Syntaxin

Syntaxins are a family of membrane integrated Q-SNARE proteins participating in exocytosis.- Domains :Syntaxins possess a single C-terminal transmembrane domain, a SNARE domain , and an N-terminal regulatory domain ....

. These proteins, together with SNAP25 (synaptosome-associated protein of 25 kDa), form a complex which serves as a binding site for the general membrane fusion machinery. Synaptobrevin/VAMP and syntaxin are believed to be involved in vesicular transport in most, if not all cells, while SNAP25 is present almost exclusively in the brain, suggesting that a ubiquitously expressed homolog of SNAP25 exists to facilitate transport vesicle/target membrane fusion in other tissues.

SNAP23 is structurally and functionally similar to SNAP25 and binds tightly to multiple syntaxins and synaptobrevins/VAMPs. It is an essential component of the high affinity receptor for the general membrane fusion machinery and is an important regulator of transport vesicle docking and fusion.

Clinical significance

In individuals with insulin resistance

Insulin resistance

Insulin resistance is a physiological condition where the natural hormone insulin becomes less effective at lowering blood sugars. The resulting increase in blood glucose may raise levels outside the normal range and cause adverse health effects, depending on dietary conditions. Certain cell types...

, SNAP23 is found to be translocated from the plasma membrane to the cytosol where it becomes associated with lipid droplets and is therefore unable to translocate GLUT-4

GLUT4

Glucose transporter type 4, also known as GLUT4, is a protein that in humans is encoded by the GLUT4 gene. GLUT4 is the insulin-regulated glucose transporter found in adipose tissues and striated muscle that is responsible for insulin-regulated glucose translocation into the cell...

 to the membrane, hindering glucose transport.

Interactions

SNAP23 has been shown to interact

Protein-protein interaction

Protein–protein interactions occur when two or more proteins bind together, often to carry out their biological function. Many of the most important molecular processes in the cell such as DNA replication are carried out by large molecular machines that are built from a large number of protein...

 with STX2

STX2

Syntaxin-2 is a protein that in humans is encoded by the STX2 gene.-Interactions:STX2 has been shown to interact with SNAP-25, SNAP23, STXBP1 and Syntaxin binding protein 3.-Further reading:...

, NAPA

NAPA (gene)

N-ethylmaleimide-sensitive factor attachment protein, alpha, also known as NAPA or alpha-SNAP, is a human gene.It is abnormally expressed in fetuses of both IVF and ICSI, which may contribute to the increase risk of birth defects in these ART....

, KIF5B

KIF5B

Kinesin-1 heavy chain is a protein that in humans is encoded by the KIF5B gene.-Interactions:KIF5B has been shown to interact with SNAP-25, SNAP23, KLC2, YWHAH and KLC1.-Further reading:...

, STX6

STX6

Syntaxin-6 is a protein that in humans is encoded by the STX6 gene.-Interactions:STX6 has been shown to interact with SNAP23, VAMP3 and VAMP4.-Further reading:...

, SYBL1

SYBL1

Vesicle-associated membrane protein 7 is a protein that in humans is encoded by the VAMP7 gene.- Function :VAMP-7 is a transmembrane protein that is a member of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor family...

, VAMP2

VAMP2

Vesicle-associated membrane protein 2 is a protein that in humans is encoded by the VAMP2 gene.-Interactions:VAMP2 has been shown to interact with STX4, SNAP-25, SNAP23, STX1A and RABAC1.-Further reading:...

, Cystic fibrosis transmembrane conductance regulator

Cystic fibrosis transmembrane conductance regulator

Cystic fibrosis transmembrane conductance regulator is a protein that in humans is encoded by the CFTR gene.CFTR is a ABC transporter-class ion channel that transports chloride and thiocyanate ions across epithelial cell membranes...

, STX4

STX4

Syntaxin-4 is a protein that in humans is encoded by the STX4 gene.-Interactions:STX4 has been shown to interact with SNAP-25, NAPA, STXBP5, SNAP23, Vesicle-associated membrane protein 8, RAB4A, TXLNB, VAMP2, VAMP3, STXBP1 and Syntaxin binding protein 3.-Further reading:...

, Syntaxin 3

Syntaxin 3

Syntaxin 3, also known as STX3, is a protein which in humans is encoded by the STX3 gene.- Function :The protein encoded by this gene is a member of the syntaxin family of cellular receptors for transport vesicles which participate in exocytosis in neutrophils...

, STX1A

STX1A

Syntaxin-1A is a protein that in humans is encoded by the STX1A gene.- Function :Synaptic vesicles store neurotransmitters that are released during calcium-regulated exocytosis. The specificity of neurotransmitter release requires the localization of both synaptic vesicles and calcium channels to...

, Vesicle-associated membrane protein 8

Vesicle-associated membrane protein 8

Vesicle-associated membrane protein 8 is a protein that in humans is encoded by the VAMP8 gene.-Interactions:Vesicle-associated membrane protein 8 has been shown to interact with STX4, SNAP23, STX1A, STX8 and STX7.-Further reading:...

, STX11

STX11

Syntaxin 11, also known as STX11, is a human gene that is a member of the t-SNARE family.-Interactions:STX11 has been shown to interact with SNAP-25 and SNAP23.-See also:* Hemophagocytic lymphohistiocytosis-Further reading:...

, VAMP3

VAMP3

Vesicle-associated membrane protein 3 is a protein that in humans is encoded by the VAMP3 gene.-Interactions:VAMP3 has been shown to interact with* BCAP31,* BVES,* SNAP23,* STX4,* STX6.-Further reading:...

 and SNAPAP

SNAPAP

SNARE-associated protein Snapin is a protein that in humans is encoded by the SNAPIN gene.-Interactions:SNAPAP has been shown to interact with SNAP-25, BLOC1S1, SNAP23, Dysbindin, TRPV1, PLDN, BLOC1S2 and RGS7.-Further reading:...

.