Tetraspanin

Tetraspanins are a family of membrane proteins found in all multicellular eukaryotes also referred to as the transmembrane 4 superfamily (TM4SF) proteins. These proteins have four transmembrane alpha-helices and two extracellular domains, one short (called the small extracellular domain or loop, SED/SEL or EC1) and one longer, typically 100 amino acid residues (the large extracellular domain/loop, LED/LEL or EC2). Although several protein families have four transmembrane alpha-helices, tetraspanins are defined by conserved amino acid sequences including four or more cysteine residues in the EC2 domain, with two in a highly conserved 'CCG' motif. Tetraspanins are often thought to act as scaffolding proteins, anchoring multiple proteins to one area of the cell membrane.[1]

Tetraspanin family
Tetraspanins have four transmembrane domains, two extracellular loops and contain a series of highly conserved amino acid residues.
Identifiers
SymbolTetraspanin
PfamPF00335
Pfam clanCL0347
InterProIPR000301
PROSITEPDOC00371
SCOP21iv5 / SCOPe / SUPFAM
TCDB8.A.40
OPM superfamily327
OPM protein5tcx
CDDcd03127
Available protein structures:
Pfam  structures / ECOD  
PDBRCSB PDB; PDBe; PDBj
PDBsumstructure summary
Hypothetical model of the tetraspanin function

Tetraspanins are highly conserved between species. Some tetraspanins can have N-linked glycosylations on the long extracellular loop (LEL, EC2) and palmitoylations at a CXXC motif in their transmembrane region.[2]

There are 34 tetraspanins in mammals, 33 of which have also been identified in humans. Tetraspanins display numerous properties that indicate their physiological importance in cell adhesion, motility, activation, and proliferation, as well as their contribution to pathological conditions such as metastasis or viral infection.

A role for tetraspanins in platelets was demonstrated by the bleeding phenotypes of CD151- and TSSC6-deficient mice, which exhibit impaired "outside-in" signalling through αIIbβ3, the major platelet integrin. it is hypothesized that tetraspanins interact with and regulate other platelet receptors.[3]

List of human tetraspanins
Protein Gene Aliases
TSPAN1 TSPAN1 TSP-1
TSPAN2 TSPAN2 TSP-2
TSPAN3 TSPAN3 TSP-3
TSPAN4 TSPAN4 TSP-4, NAG-2
TSPAN5 TSPAN5 TSP-5
TSPAN6 TSPAN6 TSP-6
TSPAN7 TSPAN7 CD231/TALLA-1/A15
TSPAN8 TSPAN8 CO-029
TSPAN9 TSPAN9 NET-5
TSPAN10 TSPAN10 OCULOSPANIN
TSPAN11 TSPAN11 CD151-like
TSPAN12 TSPAN12 NET-2
TSPAN13 TSPAN13 NET-6
TSPAN14 TSPAN14
TSPAN15 TSPAN15 NET-7
TSPAN16 TSPAN16 TM4-B
TSPAN17 TSPAN17
TSPAN18 TSPAN18
TSPAN19 TSPAN19
TSPAN20 UPK1B UP1b, UPK1B
TSPAN21 TSPAN21 UP1a, UPK1A
TSPAN22 PRPH2 RDS, PRPH2
TSPAN23 TSPAN23 ROM1
TSPAN24 CD151 CD151
TSPAN25 CD53 CD53
TSPAN26 CD37 CD37
TSPAN27 CD82 CD82
TSPAN28 CD81 CD81
TSPAN29 CD9 CD9
TSPAN30 CD63 CD63
TSPAN31 TSPAN31 SAS
TSPAN32 TSPAN32 TSSC6
TSPAN33 TSPAN33

See also

Relevance to parasite vaccines

The schistosome worms make two tetraspanins: TSP-1 and TSP-2. TSP-2 antibodies are found in some people who seem to have immunity to schistosome infection (Schistosomiasis).[4]

References
  1. Hemler ME (2005). "Tetraspanin functions and associated microdomains". Nat. Rev. Mol. Cell Biol. 6 (10): 801–11. doi:10.1038/nrm1736. PMID 16314869. S2CID 5906694.
  2. Wright MD, Tomlinson MG (1994). "The ins and outs of the transmembrane 4 superfamily". Immunol. Today. 15 (12): 588–94. doi:10.1016/0167-5699(94)90222-4. PMID 7531445.
  3. Goschnick MW, Lau LM, Wee JL, Liu YS, Hogarth PM, Robb LM, Hickey MJ, Wright MD, Jackson DE (2006). "Impaired "outside-in" integrin alphaIIbbeta3 signaling and thrombus stability in TSSC6-deficient mice". Blood. 108 (6): 1911–8. doi:10.1182/blood-2006-02-004267. PMID 16720835.
  4. Scientific American May 2008, referring to McManus & Loukas Clinical Microbiology reviews V21,N1,p225-242 (Jan 2008)
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