SEC61B
Function
Component of SEC61 channel-forming translocon complex that mediates transport of signal peptide-containing precursor polypeptides across the endoplasmic reticulum (ER) (PubMed:12475939). Forms a ribosome receptor and a gated pore in the ER membrane, both functions required for cotranslational translocation of nascent polypeptides (PubMed:12475939). 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 (PubMed:32820719, PubMed:36261522). The SEC61 channel cooperates with the translocating protein TRAM1 to import nascent proteins into the ER (PubMed:19121997).
Involvement in disease
Loss-of-function SEC61B variations may cause autosomal dominant polycystic liver disease (PCLD) in patients that lack variations in known causative genes, such as PRKCSH and SEC63.
Sequence Similarities
Belongs to the SEC61-beta family.
Cellular localization
- Endoplasmic reticulum membrane
- Single-pass membrane protein
Alternative names
Protein transport protein Sec61 subunit beta, SEC61B