N-ethylmaleimide-sensitive factor Attachment Protein Alpha, also known as SNAP-α, is a

SNAP Snap or SNAP may refer to: Arts and entertainment * ''Snap'', the original release title for the 2013 film ''Enter the Dangerous Mind'' *''Snap'' (TV series), a CITV programme * ''The Stanly News and Press'', a newspaper in Albemarle, North Carol ...

protein that is involved in the intra-cellular trafficking and fusing of vesicles to target membranes in cells.

Function

The '

SNARE SNARE proteins – " SNAP REceptor" – are a large protein family consisting of at least 24 members in yeasts, more than 60 members in mammalian cells, and some numbers in plants. The primary role of SNARE proteins is to mediate vesicle fu ...

hypothesis' is a model explaining the process of docking and fusion of

vesicles Vesicle may refer to: ; In cellular biology or chemistry * Vesicle (biology and chemistry), a supramolecular assembly of lipid molecules, like a cell membrane * Synaptic vesicle ; In human embryology * Vesicle (embryology), bulge-like features o ...

to their target

membranes A membrane is a selective barrier; it allows some things to pass through but stops others. Such things may be molecules, ions, or other small particles. Membranes can be generally classified into synthetic membranes and biological membranes. Bi ...

. According to this model, membrane

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

s from the vesicle (v-SNAREs) and proteins from the target membrane (t-SNAREs) govern the specificity of vesicle targeting and docking through mutual recognition. Once the 2 classes of SNAREs bind to each other, they form a complex that recruits the general elements of the fusion apparatus, namely

NSF NSF may stand for: Political organizations *National Socialist Front, a Swedish National Socialist party *NS-Frauenschaft, the women's wing of the former German Nazi party *National Students Federation, a leftist Pakistani students' political gr ...

(N-ethylmaleimide-sensitive factor) and

s (soluble NSF-attachment proteins), to the site of membrane fusion, thereby forming the 20S fusion complex. Alpha- and gamma-SNAP are found in a wide range of tissues and act synergistically in intra-Golgi transport. The sequence of the predicted 295-amino acid human protein encoded by NAPA shares 37%, 60%, and 67% identity with the sequences of

yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constitut ...

, ''

Drosophila ''Drosophila'' () is a genus of flies, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or (less frequently) pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species ...

'', and squid alpha-SNAP, respectively. Platelets contain some of the same proteins, including NSF, p115/TAP, alpha-SNAP (this protein), gamma-SNAP, and the t-SNAREs syntaxin-2 and syntaxin-4, that are used in many vesicular transport processes in other cell types. Platelet exocytosis uses a molecular mechanism similar to that used by other secretory cells, such as neurons, although the proteins used by the platelet and their modes of regulation may be quite different.

Clinical significance

NAPA is abnormally expressed in fetuses of both

IVF In vitro fertilisation (IVF) is a process of fertilisation where an egg is combined with sperm in vitro ("in glass"). The process involves monitoring and stimulating an individual's ovulatory process, removing an ovum or ova (egg or eggs) f ...

and

ICSI ICSI may refer to: * Intracytoplasmic sperm injection, a medical technique used in assisted reproduction * International Computer Science Institute, a non-profit research lab in Berkeley, California * Institute of Company Secretaries of India ...

, which may contribute to the increased risk of birth defects in these methods of

assisted reproductive technology Assisted reproductive technology (ART) includes medical procedures used primarily to address infertility. This subject involves procedures such as in vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI), cryopreservation of gametes o ...

(ART).

Interactions

NAPA has been shown to

interact Advocates for Informed Choice, dba interACT or interACT Advocates for Intersex Youth, is a 501(c)(3) nonprofit organization using innovative strategies to advocate for the legal and human rights of children with intersex traits. The organizati ...

with: *

, *

SNAP23 Synaptosomal-associated protein 23 is a protein that in humans is encoded by the ''SNAP23'' gene. Two alternative transcript variants encoding different protein isoforms have been described for this gene. Function Specificity of vesicular tran ...

, *

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 local ...

, *

STX4 Syntaxin-4 is a protein that in humans is encoded by the ''STX4'' gene. Interactions STX4 has been shown to interact with: * Gelsolin, * NAPA, * RAB4A, * SNAP-25, * SNAP23, * STXBP1, * STXBP5, * Syntaxin binding protein 3, * TXLNB, ...

, *

STX5 Syntaxin-5 is a protein that in humans is encoded by the ''STX5'' gene. Interactions STX5 has been shown to interact with: * BET1L, * GOSR1, * GOSR2, * NAPA, and * USO1 General vesicular transport factor p115 is a protein that in human ...

. *

ORAI1 Calcium release-activated calcium channel protein 1 is a calcium selective ion channel that in humans is encoded by the ''ORAI1'' gene. Orai channels play an important role in the activation of T-lymphocytes. The loss of function mutation of Orai ...

STIM1 Stromal interaction molecule 1 is a protein that in humans is encoded by the ''STIM1'' gene. STIM1 has a single transmembrane domain, and is localized to the endoplasmic reticulum, and to a lesser extent to the plasma membrane. Even though the pro ...

Function

Clinical significance

Interactions

References

Further reading