Tetraspanin, extracellular domain or large extracellular loop (LEL), TM4SF2_6_like subfamily. Tetraspanins are trans-membrane proteins with 4 trans-membrane segments. Both the N- and C-termini lie on the intracellular side of the membrane. This alignment model spans the extracellular domain between the 3rd and 4th trans-membrane segment. Tetraspanins are involved in diverse processes and their various functions may relate to their ability to act as molecular facilitators. Tetraspanins associate laterally with one another and cluster dynamically with numerous parnter domains in membrane microdomains, forming a network of multimolecular complexes, the "tetraspanin web". This subfamily contaions transmembrane 4 superfamily 2 (TM4SF2) or Tspan-7, transmembrane 4 superfamily 6 (TM4SF6) or Tspan-6, and related proteins. TM4SF2 has been identified as involved in some forms of X-linked mental retardation.
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