Surfeit locus protein 4
1_MGQND 6_ LMGTA 11_ EDFAD 16_ QFLRV 21_ TKQYL 26_ PHVAR 31_ LCLIS 36_ TFLED 41_ GIRMW 46_ FQWSE 51_ QRDYI 56_ DTTWN 61_ CGYLL 66_ ASSFV 71_ FLNLL 76_ GQLTG 81_ CVLVL 86_ SRNFV 91_ QYACF 96_ GLFGI 101_ IALQT 106_ IAYSI 111_ LWDLK 116_ FLMRN 121_ LALGG 126_ GLLLL 131_ LAESR 136_ SEGKS 141_ MFAGV 146_ PTMRE 151_ SSPKQ 156_ YMQLG 161_ GRVLL 166_ VLMFM 171_ TLLHF 176_ DASFF 181_ SIVQN 186_ IVGTA 191_ LMILV 196_ AIGFK 201_ TKLAA 206_ LTLVV 211_ WLFAI 216_ NVYFN 221_ AFWTI 226_ PVYKP 231_ MHDFL 236_ KYDFF 241_ QTMSV 246_ IGGLL 251_ LVVAL 256_ GPGGV 261_SMDEK
1: Endoplasmic reticulum cargo receptor that mediates the export of lipoproteins by recruiting cargos into COPII vesicles to facilitate their secretion (PubMed:29643117, PubMed:30251625, PubMed:33186557). Acts as a cargo receptor for lipoproteins bearing both APOB and APOA1, thereby regulating lipoprotein delivery and the maintenance of lipid homeostasis (PubMed:29643117, PubMed:33186557). Synergizes with the GTPase SAR1B to mediate transport of circulating lipoproteins (PubMed:33186557). Promotes the secretion of PCSK9 (PubMed:30251625). Also mediates the efficient secretion of erythropoietin (EPO) (PubMed:32989016). May also play a role in the maintenance of the architecture of the endoplasmic reticulum-Golgi intermediate compartment and of the Golgi (PubMed:18287528)