Large proline-rich protein BAG6 (BAG6)

Functions as part of a cytosolic protein quality control complex, the BAG6/BAT3 complex, which preserves these customer proteins in a soluble state and participates to their delivery to the endoplasmic reticulum or rather can encourage their sorting to the proteasome where they undergo degradation (PubMed:20516149, PubMed:21636303, PubMed:21743475, PubMed:28104892). The BAG6/BAT3 complex is included in the post-translational delivery of tail-anchored/type II transmembrane proteins to the endoplasmic reticulum membrane.

Recruited to ribosomes, it interacts with the transmembrane region of newly synthesized tail-anchored proteins and collectively with SGTA and ASNA1 mediates their delivery to the endoplasmic reticulum (PubMed:20516149, PubMed:20676083, PubMed:28104892, PubMed:25535373). Client proteins which can't be correctly delivered to the endoplasmic reticulum are ubiquitinated by RNF126, an E3 ubiquitin-protein ligase associated with BAG6 and are sorted to the proteasome (PubMed:24981174, PubMed:28104892, PubMed:27193484).