High impact information on PEP12

• Under non-permissive conditions, vps45tsf (SEC1 homolog) and pep12/vps6tsf (endosomal t-SNARE) mutants efficiently sort alkaline phosphatase (ALP) to the vacuole while multiple soluble vacuolar proteins and the membrane protein carboxypeptidase yscS (CPS) are no longer delivered to the vacuole [1].
• The acidification defect of vpl3 and vpl6 mutants correlated with a marked deficiency in vacuolar ATPase activity, diminished levels of two immunoreactive subunits of the protontranslocating ATPase (H+-ATPase) in purified vacuolar membranes, and accumulation of the intracellular portion of PrA as the precursor species [2].
• One class A mutant (vpt13) is very sensitive to low pH and exhibits a defect in vacuole acidification [3].
• The Arabidopsis cDNA (aPEP12) potentially encodes a 31-kDa protein which is homologous to yeast Pep12 and to other members of the syntaxin family, indicating that this protein may function in the docking or fusion of transport vesicles with the vacuolar membrane in plant cells [4].
• The yeast Pep12 protein is a syntaxin homologue which may function in the trafficking of vesicles from the trans-Golgi network to the vacuole [4].

Biological context of PEP12

• Temperature-sensitive-for-function (tsf) and dominant negative mutations in PEP12, encoding a putative SNARE vesicle receptor on the endosome, and tsf mutations in VAC1, a gene implicated in vacuole inheritance and vacuolar protein sorting, were constructed and used to demonstrate that Pep12p and Vac1p are components of the VPS pathway [5].
• This analysis demonstrated that both VPS45 and PEP12 are allele-specific high-copy suppressors of pep7-20 mutant phenotypes [6].
• To identify the functionally relevant interacting proteins, we analyzed all of the available gene deletion mutants and found three (vps36 Delta, pep12 Delta, and tlg2 Delta) that induce STRE and also repress pheromone-dependent transcription [7].

Anatomical context of PEP12

• The PEP12 homolog Pth1p (Pep twelve homolog 1) is predicted to be similar in size to Pep12p, the endosomal syntaxin homolog that mediates docking of Golgi-derived transport vesicles and, like other members of the syntaxin family, is predicted to be a cytoplasmically oriented, integral membrane protein with a C-terminal transmembrane domain [8].
• Genetic interactions between a pep7 mutation and the PEP12 and VPS45 genes: evidence for a novel SNARE component in transport between the Saccharomyces cerevisiae Golgi complex and endosome [6].
• Vacuolar morphology of vps33Delta cells resembles that of cells lacking both Vam3p and the endosomal syntaxin Pep12p, suggesting that Vps33p may function with these syntaxins at the vacuole and the endosome [9].

Associations of PEP12 with chemical compounds

• On sucrose gradients, membrane-associated Mos10 cofractionated with the endosomal t-SNARE Pep12, pointing to an endosomal localization of Mos10 [10].

Regulatory relationships of PEP12

• High expression of the yeast syntaxin-related Vam3 protein suppresses the protein transport defects of a pep12 null mutant [11].

Other interactions of PEP12

• The mutant vpt13 is deficient in vacuolar acidification but possesses a morphologically normal vacuole, whereas vpt16 is devoid of any vacuole-like structure [12].

Analytical, diagnostic and therapeutic context of PEP12

• Confocal laser scanning immunofluorescence studies performed on tobacco (Nicotiana tabacum) BY-2 cells revealed high degrees of colabeling between all three retromer antisera and the prevacuolar compartment (PVC) markers PEP12 and vacuolar sorting receptor VSR(At-1) [13].
• Morphological analysis by electron microscopy revealed that pep12 cells accumulate 40- to 50-nm vesicles [14].

References