Plays a role in the assembly and membrane stacking of the Golgi cisternae, and in the process by which Golgi stacks reform after breakdown during mitosis and meiosis (PubMed:10487747, PubMed:21515684, PubMed:22523075). May regulate the intracellular transport and presentation of a defined set of transmembrane proteins, such as transmembrane TGFA (PubMed:11101516). Required for normal acrosome formation during spermiogenesis and normal male fertility, probably by promoting colocalization of JAM2 and JAM3 at contact sites between germ cells and Sertoli cells (By similarity). Mediates ER stress-induced unconventional (ER/Golgi-independent) trafficking of core-glycosylated CFTR to cell membrane (PubMed:21884936, PubMed:27062250, PubMed:28067262). Homodimer. Homooligomer. ER stress induces phosphorylation-dependent monomerization (PubMed:27062250). Interacts with BLZF1/Golgin 45 (PubMed:11739401). Identified in a complex with RAB2 and GORASP2 (PubMed:11739401). Interacts with JAM2 and JAM3 (By similarity). Interacts with members of the p24 cargo receptors (PubMed:11739402). Interacts with CNIH1 and the cytoplasmic domain of transmembrane TGFA, prior its transit in the trans-Golgi (PubMed:11101516, PubMed:17607000). Interacts with KCTD5 (PubMed:19361449). Interacts with TMED2 and TMED3 (By similarity). Interacts with SEC16A in response to ER stress (PubMed:28067262). Interacts (via PDZ GRASP-type 1 domain) with core-glycosylated CFTR in response to ER stress (PubMed:21884936). Detected in the intermediate Golgi, membrane-associated (By similarity). ER stress triggers its relocalization from Golgi to ER membrane (PubMed:27062250, PubMed:28067262). Myristoylated (PubMed:11101516). Myristoylation is essential for the Golgi targeting (By similarity). Palmitoylated. Phosphorylated in mitotic cells (PubMed:11408587). ER stress-induced phosphorylation at Ser-441 induces monomerization and subsequent relocalization from Golgi to ER which is essential for mediating unconventional (ER/Golgi-independent) trafficking of CFTR to the cell membrane (PubMed:21884936, PubMed:27062250). Belongs to the GORASP family.