Serine/threonine-protein kinase required for cytoplasm to vacuole transport (Cvt) and autophagy as a part of the autophagy-specific VPS34 PI3-kinase complex I. This complex is essential to recruit the ATG8-phosphatidylinositol conjugate and the ATG12-ATG5 conjugate to the pre-autophagosomal structure. Is also involved in endosome-to-Golgi retrograde transport as part of the VPS34 PI3-kinase complex II. This second complex is required for the endosome-to-Golgi retrieval of PEP1 and KEX2, and the recruitment of VPS5 and VPS7, two components of the retromer complex, to endosomal membranes (probably through the synthesis of a specific pool of phosphatidylinositol 3-phosphate recruiting the retromer to the endosomes). By regulating VPS34 kinase activity, VPS15 appears to be essential for the efficient delivery of soluble hydrolases to the yeast vacuole. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Component of the autophagy-specific VPS34 PI3-kinase complex I composed of VPS15, VPS30, VPS34, ATG14 and ATG38; and of the VPS34 PI3-kinase complex II composed of VPS15, VPS30, VPS34 and VPS38. Truncation of 30 residues from the C-terminus results in a temperature-conditional defect in protein sorting. Autophosphorylated. Decreases TORC1 activation in response to glutamine. Present with 279 molecules/cell in log phase SD medium. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.