Component of SEC61 channel-forming translocon complex that mediates transport of signal peptide-containing precursor polypeptides across the endoplasmic reticulum (ER) (  ). Forms a ribosome receptor and a gated pore in the ER membrane, both functions required for cotranslational translocation of nascent polypeptides ( ). May cooperate with auxiliary protein SEC62, SEC63 and HSPA5/BiP to enable post-translational transport of small presecretory proteins (, ). The SEC61 channel is also involved in ER membrane insertion of transmembrane proteins: it mediates membrane insertion of the first few transmembrane segments of proteins, while insertion of subsequent transmembrane regions of multi-pass membrane proteins is mediated by the multi-pass translocon (MPT) complex (, ). The SEC61 channel cooperates with the translocating protein TRAM1 to import nascent proteins into the ER . Controls the passive efflux of calcium ions from the ER lumen to the cytosol through SEC61 channel, contributing to the maintenance of cellular calcium homeostasis . Plays a critical role in nephrogenesis, specifically at pronephros stage (By similarity).
Subcellular locations: Endoplasmic reticulum membrane
Localizes exclusively in granular structures in the endoplasmic reticulum (ER).
Expressed in proximal and distal tubules in kidney (at protein level).