Background：TRAPA(translocon-associated protein subunit alpha), also known as SSR1(signal sequence receptor subunit alpha), is a 34-kDa single-spanning membrane glycoprotein of the endoplasmic reticulum(ER)(PMID: 8050590). It is a part of the tetrameric TRAP complex(TRAP-alpha, TRAP-beta, TRAP-delta and TRAP-gamma) which functions in regulating the retention of ER resident proteins(PMID: 7916687). The TRAP complex is also involved in endoplasmic reticulum-associated degradation(ERAD)(PMID: 17380188).
