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J Cell Biol

Title:		The Golgi-resident protease Kex2 acts in conjunction with Prm1 to facilitate cell fusion during yeast mating
Author(s):		Heiman MG; Engel A; Walter P;
Address:		"Howard Hughes Medical Institute, Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA"
Journal Title:		J Cell Biol
Year:		2007
Volume:		20070108
Issue:		2
Page Number:		209 - 222
DOI:		10.1083/jcb.200609182
ISSN/ISBN:		0021-9525 (Print) 1540-8140 (Electronic) 0021-9525 (Linking)
Abstract:		"The molecular machines that mediate cell fusion are unknown. Previously, we identified a multispanning transmembrane protein, Prm1 (pheromone-regulated membrane protein 1), that acts during yeast mating (Heiman, M.G., and P. Walter. 2000. J. Cell Biol. 151:719-730). Without Prm1, a substantial fraction of mating pairs arrest with their plasma membranes tightly apposed yet unfused. In this study, we show that lack of the Golgi-resident protease Kex2 strongly enhances the cell fusion defect of Prm1-deficient mating pairs and causes a mild fusion defect in otherwise wild-type mating pairs. Lack of the Kex1 protease but not the Ste13 protease results in similar defects. Deltakex2 and Deltakex1 fusion defects were suppressed by osmotic support, a trait shared with mutants defective in cell wall remodeling. In contrast, other cell wall mutants do not enhance the Deltaprm1 fusion defect. Electron microscopy of Deltakex2-derived mating pairs revealed novel extracellular blebs at presumptive sites of fusion. Kex2 and Kex1 may promote cell fusion by proteolytically processing substrates that act in parallel to Prm1 as an alternative fusion machine, as cell wall components, or both"
Keywords:		Adenosine Triphosphatases/genetics/physiology Carboxypeptidases/genetics/physiology Cation Transport Proteins/genetics/physiology Cell Membrane/metabolism/ultrastructure Cell Wall/drug effects/metabolism/ultrastructure Congo Red/pharmacology Cytoplasmic V;
Notes:		"MedlineHeiman, Maxwell G Engel, Alex Walter, Peter eng 2007/01/11 J Cell Biol. 2007 Jan 15; 176(2):209-22. doi: 10.1083/jcb.200609182. Epub 2007 Jan 8"