title: Immunoisolation of Kex2p-containing organelles from yeast demonstrates colocalisation of three processing proteinases to a single Golgi compartment.
abstract: One of the Golgi compartments of Saccharomyces cerevisiae is defined by the presence of a specific endoproteinase, Kex2p, which cleaves precursor polypeptides at pairs of basic residues. We have used antibodies directed against the cytoplasmically disposed C-terminal domain of Kex2p to develop an immuno-affinity procedure for the isolation of Kex2p-containing organelles. The method gives a high yield of sealed organelles that are essentially free of contamination from other secretory pathway organelles while being significantly enriched for two other late Golgi enzymes, dipeptidylaminopeptidase A and the Kex1 carboxypeptidase. Our findings provide clear evidence for a single yeast Golgi compartment containing all three late-processing enzymes, which is likely to be the functional equivalent in yeast of the mammalian trans-Golgi network.
authors.affiliation: Department of Biochemistry, University of Edinburgh, UK.
authors.forename: N J
authors.initials: NJ
authors.lastname: Bryant
authors.forename: A
authors.initials: A
authors.lastname: Boyd
mesh_terms: D002268:Carboxypeptidases / Q000378:metabolism; D002499:Centrifugation, Density Gradient; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D015151:Immunoblotting; D007150:Immunohistochemistry; D009154:Mutation; D015388:Organelles / Q000201:enzymology; D043484:Proprotein Convertases; D011499:Protein Processing, Post-Translational; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000648:ultrastructure*; D029701:Saccharomyces cerevisiae Proteins; D013381:Subtilisins / Q000378:metabolism*
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D002268:Carboxypeptidases; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; C078874:carboxypeptidase D; D043484:Proprotein Convertases; D013381:Subtilisins; C058751:KEX2 protein, S cerevisiae