9.B.392.  The Golgi Apparatus Golgin (Golgin) Family

These proteins are involved in maintaining the Golgi structure, stimulating the formation of Golgi stacks and ribbons (Diao et al. 2003), and in intra-Golgi retrograde transport. Coiled-coil proteins of the golgin family have been implicated in intra-Golgi transport through tethering coat protein complex I (COPI) vesicles. The p115-golgin tether is the best studied. Malsam et al. 2005 characterized the golgin-84-CASP tether. The vesicles bound by this tether were strikingly different from those bound by the p115-golgin tether in that they lacked members of the p24 family of putative cargo receptors and contained enzymes instead of anterograde cargo. Microinjected golgin-84 or CASP inhibited Golgi-enzyme transport to the endoplasmic reticulum, further implicating this tether in retrograde transport. These and other golgins may modulate the flow patterns within the Golgi stack (Malsam et al. 2005).

The plant Golgi apparatus is responsible for the processing of proteins received from the ER, and their distribution to multiple destinations within the cell. Golgi matrix components, such as golgins, are tethering factors that mediate the physical connections between Golgi bodies and the ER. Golgins are  anchored to the Golgi membrane by the C-terminus either throughTMSs or interaction with small regulatory GTPases. The golgin N-terminus contains long coiled-coil domains which consist of a number of alpha-helices wrapped around each other to form a structure similar to a rope being made from several strands, reaching into the cytoplasm. In animal cells golgins are implicated in specific recognition of cargo. The plant golgin Atgolgin-84A is a tethering factor at the ER-Golgi interface.  Without it, transport between the ER and Golgi bodies is impaired, and cargo proteins are redirected to the vacuole (Vieira et al. 2020). Both O- and N-glycans appear to function as generic Golgi export signals at the trans-Golgi to promote exocytic trafficking (Sun et al. 2020).