Signal recognition particle receptor subunit beta

Signal recognition particle receptor subunit beta (SR-β) is a 271-amino acid component of the signal recognition particle (SRP) receptor complex located at the endoplasmic reticulum membrane. It functions to direct nascent secretory proteins to the ER membrane system in coordination with the SRP complex, ensuring proper protein targeting during translation (UniProt: Q9Y5M8).

SR-β is involved in the fundamental cellular process of protein synthesis and secretion, with particular relevance to ER-resident and secreted proteins. No baseline disease associations are documented in UniProt, though the protein's role in protein quality control and ER function connects it to broader cellular homeostasis pathways.

In Alzheimer's disease, SR-β is downregulated in human post-mortem AD brain tissue compared to age-matched controls (mean log2 fold-change: −0.281), as measured by quantitative proteomics across subcellular fractions (Chaparral AD proteomics). This reduced expression may reflect compromised protein trafficking or ER stress in the AD brain, though the functional consequence of this downregulation requires further investigation.