pfam03896: TRAP_alpha (This model is not part of the current CDD release)
Translocon-associated protein (TRAP), alpha subunit
The alpha-subunit of the TRAP complex (TRAP alpha also known as signal sequence receptor 1/alpha subunit, SSRA)) is a single-spanning membrane protein of the endoplasmic reticulum (ER) which is found in proximity of nascent polypeptide chains translocating across the membrane. TRAP complex consists of four subunits (alpha, beta, gamma, delta) and localises in the ER membrane. It associates with the Sec61 translocon as a heterotetramer. It also interacts with palmitoylated calnexin (CALX), the interaction is required for efficient folding of glycosylated proteins. TRAP complex may also be involved in endoplasmic reticulum-associated degradation. TRAP-alpha plays a critical role in the biosynthesis of insulin, being involved in preproinsulin translocation and proinsulin trafficking which may contribute to the pathogenesis of type 2 diabetes. This entry also includes IRC22 from fungi, which show sequence and structural similarities with TRAP-alpha. The function of IRC22 is not yet known.
Jiyao W et al.(2023). "The conserved domain database in 2023.",