Involved in vesicular trafficking at the Golgi apparatus level. May play a role in delivery of transport vesicles containing GPI-linked proteins from the trans-Golgi network through its interaction with MACF1. Involved in endosome-to-Golgi trafficking (PubMed:29084197). Homodimer (PubMed:14718928). Interacts with RAB6A (PubMed:10209123). Interacts with GTP-bound ARL1 and ARL3 (PubMed:11303027, PubMed:14580338, PubMed:14718928). Interacts with MACF1 (PubMed:15265687). Directly interacts with TBC1D23 (PubMed:29084197). Interacts with FAM91A1; this interaction may be mediated by TBC1D23 (PubMed:29084197). Additional isoforms seem to exist. Extended rod-like protein with coiled-coil domains. Antibodies against GOLGA4 are present in sera from patients with Sjoegren syndrome. Sera from patients with Sjoegren syndrome often contain antibodies that react with normal components of the Golgi complex. Extended N-terminus.