Protein transport protein Sec61 subunit beta

SEC61B encodes the beta subunit of the SEC61 translocon complex, a core component of the endoplasmic reticulum (ER) protein translocation machinery (UniProt: P60468). This 96-amino acid protein forms part of the channel-forming translocon that mediates cotranslational translocation of nascent polypeptides across the ER membrane and facilitates ER insertion of transmembrane proteins. SEC61B cooperates with translocase components like TRAM1 to enable proper protein import and membrane insertion.

SEC61B functions within the secretory pathway and ER proteostasis network. No disease associations are listed in UniProt for this protein, though impaired ER function and protein translocation are implicated in various pathological contexts.

SEC61B shows increased abundance in Alzheimer's disease brain tissue. Analysis of post-mortem AD brain versus age-matched controls using quantitative proteomics (TMT-labeled, DDA) detected SEC61B upregulation with a mean log2 fold-change of 0.32 (Chaparral AD proteomics). This modest elevation across one subcellular fraction may reflect compensatory or pathological changes in ER translocation capacity associated with AD neurodegeneration.