Tetraspanin, extracellular domain or large extracellular loop (LEL), CD53_Like family. 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". CD53 is a tetraspanin of the lymphoid-myeloid lineage and has been implicated in apoptosis protection. It associates with integrin alpha4beta1. Some of the cellular responses modulated by CD53 may be mediated by JNK activation and/or via the AKT pathway.
Jiyao W et al.(2023). "The conserved domain database in 2023.",