Involved in maintaining Golgi structure. Stimulates the formation of Golgi stacks and ribbons. Involved in intra-Golgi retrograde transport. Homodimer. Interacts with RAB1A that has been activated by GTP-binding, and possibly also with OCRL1. Interacts with isoform CASP of CUX1. Found throughout the Golgi, both on cisternae and, at higher abundance, on the tubulo-vesicular structures of the cis-Golgi network. Ubiquitous. Highly expressed in seminiferous tubules and Leydig cells in testis, and detected at much lower levels in the other tissues tested. Expression is very low or not detectable in spermatozoa. Highly phosphorylated during mitosis. Phosphorylation is barely detectable during interphase. A chromosomal aberration involving GOLGA5 is found in papillary thyroid carcinomas (PTCs). Translocation t(10;14)(q11;q32) with RET. The translocation generates the RET/GOLGA5 (PTC5) oncogene. Chimeric cDNA. A chimeric cDNA originating from chromosomes 14 and 10.