Mediates post-translational transport of precursor polypeptides across endoplasmic reticulum (ER). Proposed to act as a targeting receptor for small presecretory proteins containing short and apolar signal peptides. Targets and properly positions newly synthesized presecretory proteins into the SEC61 channel-forming translocon complex, triggering channel opening for polypeptide translocation to the ER lumen. The ER translocon complex that consists of channel-forming core components SEC61A1, SEC61B and SEC61G and different auxiliary components such as SEC62 and SEC63 (PubMed:10860986, PubMed:10799540). Interacts with SEC61B (By similarity). Pancreas. Belongs to the SEC62 family.