Required for normal Golgi function and necessary during spermatogenesis. Required for cleavage furrow ingression during cytokinesis in dividing spermatocytes and for the extensive polarized cell growth that accompanies spermatid elongation. Component of the conserved oligomeric Golgi complex which is composed of eight different subunits and is required for normal Golgi morphology and localization. Localized to Golgi membrane throughout spermatogenesis, as seen in spermatocytes and differentiating spermatids. Expressed in embryos, and adult males and females. Males are sterile. Belongs to the COG5 family.