The Acb1 secretion pathway. Cytosolic Acb1 is packaged into autophagosomes, which fuse with early endosomes. The early endosomes containing Acb1 either fuse directly with the cell surface or more likely mature into an MVB. The MVB fuses with the cell surface to release exosomes containing Acb1. Grh1 is required for the secretion of Acb1 and has to be membrane associated for its role in this pathway. However, the exact site of action for Grh1 in unconventional secretion remains unknown.