Ubiquitin-like protein 4A (Ubiquitin-like protein GDX)
1_MQLTV 6_ KALQG 11_ RECSL 16_ QVPED 21_ ELVST 26_ LKQLV 31_ SEKLN 36_ VPVRQ 41_ QRLLF 46_ KGKAL 51_ ADGKR 56_ LSDYS 61_ IGPNS 66_ KLNLV 71_ VKPLE 76_ KVLLE 81_ EGEAQ 86_ RLADS 91_ PPPQV 96_ WQLIS 101_ KVLAR 106_ HFSAA 111_ DASRV 116_ LEQLQ 121_ RDYER 126_ SLSRL 131_ TLDDI 136_ ERLAS 141_ RFLHP 146_ EVTET 151_MEKGF
1: As part of a cytosolic protein quality control complex, the BAG6/BAT3 complex, maintains misfolded and hydrophobic patches-containing proteins in a soluble state and participates in their proper delivery to the endoplasmic reticulum or alternatively can promote their sorting to the proteasome where they undergo degradation (PubMed:20676083, PubMed:21636303, PubMed:21743475, PubMed:28104892). The BAG6/BAT3 complex is involved 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 together with SGTA and ASNA1 mediates their delivery to the endoplasmic reticulum (PubMed:20676083, PubMed:25535373, PubMed:28104892). Client proteins that cannot be properly delivered to the endoplasmic reticulum are ubiquitinated and sorted to the proteasome (PubMed:28104892). Similarly, the BAG6/BAT3 complex also functions as a sorting platform for proteins of the secretory pathway that are mislocalized to the cytosol either delivering them to the proteasome for degradation or to the endoplasmic reticulum (PubMed:21743475). The BAG6/BAT3 complex also plays a role in the endoplasmic reticulum-associated degradation (ERAD), a quality control mechanism that eliminates unwanted proteins of the endoplasmic reticulum through their retrotranslocation to the cytosol and their targeting to the proteasome. It maintains these retrotranslocated proteins in an unfolded yet soluble state condition in the cytosol to ensure their proper delivery to the proteasome (PubMed:21636303)