Golgi-associated tethers capture vesicles from specific membrane recycling pathways

During maturation of a Golgi cisterna, a series of vesicular transport pathways recycle resident Golgi proteins. Recycling vesicles are captured by Golgi-associated tethers. Here, we examined three of these recycling pathways in Saccharomyces cerevisiae. For each pathway, we determined which tethers were present on a maturing cisterna while the vesicles were arriving, and we ectopically localized different tethers to determine which ones captured the vesicles. Those approaches yielded mutually consistent results. At an intermediate stage of cisternal maturation, the golgin Sgm1 tethers vesicles from an intra-Golgi recycling pathway dependent on COPI. At a late stage of cisternal maturation, the golgin Imh1 and the multi-subunit GARP complex tether vesicles from an intra-Golgi recycling pathway dependent on the AP-1 and Ent5 clathrin adaptors. This involvement of GARP in intra-Golgi recycling had not previously been appreciated. We found no evidence for the earlier proposal that GARP tethers vesicles traveling from prevacuolar endosome compartments to the trans-Golgi network, but Imh1 does tether those vesicles. Our data contribute to an integrated and increasingly mechanistic picture of Golgi dynamics.