Human diseases caused by multi-organellar disorders . Proteins are delivered to the yeast vacuole by three different cellular pathways. The pathway that is best known and most thoroughly investigated is a branch of the secretory pathway.
Proteins move from there to the vacuole.
The direct route bypasses the endosome and is dependent on the AP3 adaptin complex. More than 50 genes are required for biogenesis of the vacuole and delivery of proteins to it. Pep12p, a syntaxin homologue, is cytoplasmically oriented and inserted C-terminally in the endosomal membrane, where it is thought to participate in vesicular fusion. It interacts with Vps45p, a Sec1p homologue, and with Pep7p. The rab5 homologue Vps21p also is required at this step.