NSF attachment protein (IPR000744)

Short name: NSF_attach

Overlapping homologous superfamilies

Family relationships



Regulated exocytosis of neurotransmitters and hormones, as well as intracellular traffic, requires fusion of two lipid bilayers. SNARE proteins are thought to form a protein bridge, the SNARE complex, between an incoming vesicle and the acceptor compartment. SNARE proteins contribute to the specificity of membrane fusion, implying that the mechanisms by which SNAREs are targeted to subcellular compartments are important for specific docking and fusion of vesicles. This mechanism involves a family of conserved proteins, members of which appear to function at all sites of constitutive and regulated secretion in eukaryotes [PMID: 7846761]. Among them are 2 types of cytosolic protein, NSF (N-ethyl-maleimide-sensitive protein) and the SNAPs (alpha-, beta- and gamma-soluble NSF attachment proteins). The yeast vesicular fusion protein, sec17, a cytoplasmic peripheral membrane protein involved in vesicular transport between the endoplasmic reticulum and the golgi apparatus, shows a high degree of sequence similarity to the alpha-SNAP family.

Alpha-SNAP is universally present in eukaryotes and acts as an adaptor protein between SNARE (integral membrane SNAP receptor) and NSF for recruitment to the 20S complex. Beta-SNAP is brain-specific and shares high sequence identity (about 85%) with alpha-SNAP. Gamma-SNAP is weakly related (about 20-25% identity) to the two other isoforms, and is ubiquitous. It may help regulate the activity of the 20S complex. The X-ray structures of vertebrate gamma-SNAP and Sec17 show similar all-helical structures consisting of an N-terminal extended twisted sheet of four tetratricopeptide repeat (TPR)-like helical hairpins and a C-terminal helical bundle [PMID: 17634982, PMID: 10445030, PMID: 16981829, PMID: 17397838, PMID: 23836889, PMID: 19762473, PMID: 12730228, PMID: 8455721].

SNAP-25 and its non-neuronal homologue Syndet/SNAP-23 are synthesized as soluble proteins in the cytosol. Both SNAP-25 and Syndet/SNAP-23 are palmitoylated at cysteine residues clustered in a loop between two N- and C-terminal coils and palmitoylation is essential for membrane binding and plasma membrane targeting. The C-terminal and the N-terminal helices of SNAP-25, are each targeted to the plasma membrane by two distinct cysteine-rich domains and appear to regulate the availability of SNAP to form complexes with SNARE [PMID: 12140265].

GO terms

Biological Process

GO:0006886 intracellular protein transport

Molecular Function

No terms assigned in this category.

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.