High impact information on VPS34

• Activation of the phosphatidylinositol 3-kinase Vps34 by a G protein alpha subunit at the endosome [1].
• The PtdIns(3)P 5-kinase activity of Fab1p, which converts the product of the Vps34p PtdIns 3-kinase PtdIns(3)P into PtdIns(3,5)P2, also is required for cargo-selective sorting into the vacuole lumen [2].
• The VPS15 and VPS34 genes encode components of a novel signal transduction complex essential for the delivery of soluble vacuolar hydrolases [3].
• The sequence of the PIK1 gene product bears similarities to that of PtdIns 3-kinases from mammals (p110) and yeast (Vps34p) [4].
• Phosphatidylinositol 3-kinase encoded by yeast VPS34 gene essential for protein sorting [5].

Biological context of VPS34

• Vac1p FYVE finger mutant missorting phenotypes were suppressed by a defective allele of VPS34 [6].
• This rapid block in vacuolar protein sorting appears to be the result of loss of PtdIns 3-kinase activity since cellular PtdIns(3)P levels decrease dramatically in vps34 temperature-sensitive mutant cells that have been incubated at the nonpermissive temperature [7].
• Two distinct Vps34 phosphatidylinositol 3-kinase complexes function in autophagy and carboxypeptidase Y sorting in Saccharomyces cerevisiae [8].
• Dominant missense mutations in a novel yeast protein related to mammalian phosphatidylinositol 3-kinase and VPS34 abrogate rapamycin cytotoxicity [9].
• The nucleotide sequence of STT4 predicts a hydrophilic protein composed of 1,900 amino acid residues, with 26% sequence identity to the yeast VPS34 gene product and 27% to the catalytic subunit of mammalian phosphatidylinositol (PI) 3-kinase, respectively [10].

Anatomical context of VPS34

• VPS15 and VPS34 encode a serine/ threonine protein kinase and a phosphatidylinositol 3-kinase, respectively, that interact at the cytoplasmic face of an intracellular membrane compartment, most likely corresponding to the late Golgi [3].
• A membrane-associated complex composed of the Vps15 protein kinase and the Vps34 phosphatidylinositol 3-kinase (PtdIns 3-kinase) is essential for the delivery of proteins to the yeast vacuole [7].
• Vps34p and Vps30p, components shared by the two complexes, localized to the PAS, vacuolar membranes, and several punctate structures that included endosomes [11].
• On the basis of the role for Vps34p in vacuolar protein sorting, we propose that the production of a specific phosphoinositide, PtdIns(3)P, is involved in regulating intracellular protein sorting reactions in eukaryotic cells [12].
• We propose that LET-512/VPS34 is required for membrane transport from the outer nuclear membrane towards the cell periphery [13].

Associations of VPS34 with chemical compounds

• A direct role for phosphoinositides in vesicular trafficking has been demonstrated by the identification of the yeast VPS34 gene encoding the phosphatidylinositol 3-kinase responsible for the synthesis of phosphatidylinositol 3-phosphate (PtdIns3P) [14].
• Subcellular fractionation and sucrose density gradients indicate that Vps15p is responsible for the association of Vps34p with an intracellular membrane fraction [15].
• Characterization of the PI 3-kinase activity of Vps34p demonstrates that it, unlike the mammalian p110 PI 3-kinase, is highly resistant to the PI 3-kinase inhibitors wortmannin and LY294002 [12].
• Using an in vivo assay in yeast that detects Vps34 PI(3)K-dependent intracellular localization of a GFP reporter protein, and in vitro lipid-binding assays, we demonstrate that cysteine-rich RING domains of the FYVE finger subfamily bind specifically to Ptdlns phosphorylated exclusively at the D-3 position of the inositol ring [16].
• Cholesterol sulfate and sulfatide inhibit the free catalytic subunit p110 alpha but fail to inhibit the homologous phosphatidylinositol 3-kinase from Saccharomyces cerevisiae (Vps34p), suggesting that these sulfated lipids act specifically on the mammalian phosphatidylinositol 3-kinase [17].

Physical interactions of VPS34

• The phosphatidylinositol 3-kinase Vps34p of the human pathogenic yeast Candida albicans is a multifunctional protein that interacts with the putative vacuolar H+ -ATPase subunit Vma7p [18].

Regulatory relationships of VPS34

• Consistent with this, mutations altering highly conserved residues in the lipid kinase domain of Vps34p lead to a dominant-negative phenotype resulting from titration of activating Vps15 proteins [7].
• We propose that Vps34 regulates the CPY, Cvt, and macroautophagy pathways through distinct sets of PtdIns(3)P-binding effectors and that Vps34 promotes protein trafficking in the Cvt pathway through activation/localization of the effector protein Etf1 [19].

Other interactions of VPS34

• In contrast, catalytically inactive Vps15p mutants do not produce a dominant mutant phenotype because they are unable to associate with Vps34p in a wild-type manner [7].
• These results indicate that Vps30p functions as a subunit of a Vps34 PtdIns 3-kinase complex(es) [8].
• They were identified by mass spectrometry to be Vps38p and Vps34p, a phosphatidylinositol (PtdIns) 3-kinase [8].
• The vps34 and vps15 mutants displayed additional phenotypes such as defects in transport of proteinase A and proteinase B, implying the existence of another PtdIns 3-kinase complex(es) [8].
• In contrast, deletions in genes that selectively confer vacuolar hydrolase sorting to the PVC or protein transport to the vacuole (i.e. VPS34 and VAM3, respectively) have no effect [20].

Analytical, diagnostic and therapeutic context of VPS34

• Chemical cross-linking and native immunoprecipitation experiments demonstrate that Vps15p and Vps34p interact as components of a hetero-oligomeric protein complex [15].
• Phosphatidylinositol 3,4,5-trisphosphate (PIP(3)) and the D3 isomers of PIP(2) are detected after treatment of cells with pervanadate; in yeast, overexpression of a phosphatidylinositol 3-kinase (VPS34) specifically increases phosphatidylinositol 3-phosphate (PI3P) [21].
• Cell fractionation studies indicated that a significant portion of the Vps34p is found associated with a particulate fraction of yeast cells [22].
• In the present paper we describe the molecular cloning of a PI3K from Drosophila, P13K_59F, that shows sequence similarity to Vps34 [23].
• Western blotting of subcellular fractions revealed that most of Vps34p in cell lysates of cw-15 (a cell wall-deficient mutant) could be recovered in a NP-40-resistant 100000 x g pellet, suggesting that the enzyme may have a location different from that found in higher plants [24].

References