Golgins in the structure and dynamics of the Golgi apparatus

Golgins are a family of coiled-coil proteins associated with the Golgi apparatus necessary for tethering events in membrane fusion and as structural supports for Golgi cisternae. Recent work has shown that golgins such as GM130, golgin-45 and p115 bind to Rab GTPases via their coiled-coil domains, and that GM130, rather than being part of a static structural matrix, is in dynamic exchange between the membrane surface and the cytoplasm. Golgins such as bicaudal-D1 and -D2 bind to Rab6, but, rather than tethering membranes together, link vesicles to the cytoskeleton, thus adding a new function for this class of proteins. Other golgins containing the Golgi targeting GRIP domain, rather than binding Rabs, interact with and are recruited to membranes by another class of GTPase, the Arls. Current evidence therefore suggests that golgins function in a variety of membrane-membrane and membrane-cytoskeleton tethering events at the Golgi apparatus, and that all these are regulated by small GTPases of the Rab and Arl families.