Plays an important role in spermatogenesis and/or testis development. Probably identical with the serologically detectable male antigen (SDM). Probably involved in maintaining Golgi structure. Homodimer. Interacts with GOLGA7. Interacts with GOPC (By similarity). Highly expressed in testis. Transcripts can be found in spermatids during spermatogenesis. No expression in Leydig cells, spermatogonia or spermatocytes. Detected at low levels in all tissues. Extended rod-like protein with coiled-coil domains. Cleaved by caspases in apoptotic cells.