Acts as component of the Sec62/63 complex which is involved in SRP-independent post-translational translocation across the endoplasmic reticulum (ER) and functions together with the Sec61 complex and bip1 in a channel-forming translocon complex. In an initial step, the signal sequence seems to bind simultaneously to sec61 and sec62. sec62 and sec63 are required for interactions between sec61 and translocating polypeptides. sec62 may affect sec61-polypeptide interactions by increasing the affinity of targeting pathways for sec61 and/or by modifying sec61 to allow more efficient polypeptide interaction. A cycle of assembly and disassembly of Sec62/63 complex from sec61 may govern the activity of the translocon (By similarity). Component of the heterotetrameric Sec62/63complex composed of sec62, sec63, sec66 and sec72. The Sec62/63 complex associates with the Sec61 complex to form the Sec complex (By similarity). Belongs to the SEC62 family.