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J Cell Biol

Title:		Novel genes involved in endosomal traffic in yeast revealed by suppression of a targeting-defective plasma membrane ATPase mutant
Author(s):		Luo W; Chang A;
Address:		"Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA"
Journal Title:		J Cell Biol
Year:		1997
Volume:		138
Issue:		4
Page Number:		731 - 746
DOI:		10.1083/jcb.138.4.731
ISSN/ISBN:		0021-9525 (Print) 1540-8140 (Electronic) 0021-9525 (Linking)
Abstract:		"A novel genetic selection was used to identify genes regulating traffic in the yeast endosomal system. We took advantage of a temperature-sensitive mutant in PMA1, encoding the plasma membrane ATPase, in which newly synthesized Pma1 is mislocalized to the vacuole via the endosome. Diversion of mutant Pma1 from vacuolar delivery and rerouting to the plasma membrane is a major mechanism of suppression of pma1(ts). 16 independent suppressor of pma1 (sop) mutants were isolated. Identification of the corresponding genes reveals eight that are identical with VPS genes required for delivery of newly synthesized vacuolar proteins. A second group of SOP genes participates in vacuolar delivery of mutant Pma1 but is not essential for delivery of the vacuolar protease carboxypeptidase Y. Because the biosynthetic pathway to the vacuole intersects with the endocytic pathway, internalization of a bulk membrane endocytic marker FM 4-64 was assayed in the sop mutants. By this means, defective endosome-to-vacuole trafficking was revealed in a subset of sop mutants. Another subset of sop mutants displays perturbed trafficking between endosome and Golgi: impaired pro-alpha factor processing in these strains was found to be due to defective recycling of the trans-Golgi protease Kex2. One of these strains defective in Kex2 trafficking carries a mutation in SOP2, encoding a homologue of mammalian synaptojanin (implicated in synaptic vesicle endocytosis and recycling). Thus, cell surface delivery of mutant Pma1 can occur as a consequence of disturbances at several different sites in the endosomal system"
Keywords:		Biological Transport/genetics Biomarkers Carrier Proteins/genetics Cell Membrane/enzymology/genetics/metabolism Endosomes/*enzymology/*genetics/metabolism Fungal Proteins/genetics Intracellular Membranes/enzymology Mating Factor *Mutagenesis Nerve Tissue;
Notes:		"MedlineLuo, W j Chang, A eng Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. 1997/08/25 J Cell Biol. 1997 Aug 25; 138(4):731-46. doi: 10.1083/jcb.138.4.731"