Phosphatidylinositol-4-phosphate-binding protein that links Golgi membranes to the cytoskeleton and may participate in the tensile force required for vesicle budding from the Golgi. Thereby, may play a role in Golgi membrane trafficking and could indirectly give its flattened shape to the Golgi apparatus. May also bind to the coatomer to regulate Golgi membrane trafficking. May play a role in anterograde transport from the Golgi to the plasma membrane and regulate secretion. Mediates the cis and medial Golgi localization of mannosyltransferases through direct binding of their cytosolic domains. Involved in vacuolar protein sorting. Homotetramer. Interacts with coatomer complex. May interact with ARF1. Phosphatidylinositol 4-phosphate-binding and oligomerization participate in the recruitment onto Golgi membranes. Present with 1850 molecules/cell in log phase SD medium. Belongs to the GOLPH3/VPS74 family.