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J Biol Chem

Title:		Protein kinase Byr2 is a target of Ras1 in the fission yeast Schizosaccharomyces pombe
Author(s):		Masuda T; Kariya K; Shinkai M; Okada T; Kataoka T;
Address:		"Department of Physiology II, Kobe University School of Medicine, Japan"
Journal Title:		J Biol Chem
Year:		1995
Volume:		270
Issue:		5
Page Number:		1979 - 1982
DOI:		10.1074/jbc.270.5.1979
ISSN/ISBN:		0021-9258 (Print) 0021-9258 (Linking)
Abstract:		"Conservation of the structure and function of Ras proteins has been observed in a variety of eukaryotic organisms. However, the nature of their downstream effectors appears to be quite divergent; adenylyl cyclase and a protein kinase Raf-1, which do not share any structural homology with each other, are effectors of Ras in the budding yeast and in higher organisms, respectively. We show here that a protein kinase Byr2, which has been known to act downstream of Ras1 in a mating pheromone signal transduction system of Schizosaccharomyces pombe, binds directly to Ras proteins in a GTP-dependent manner. The region of Byr2 responsible for the Ras binding was mapped by a gene deletion analysis to its N-terminal segment of 206 amino acid residues, which does not possess any significant homology with the other effectors of Ras. The affinity of the Byr2 N terminus for Saccharomyces cerevisiae Ras2 was determined by measuring its activity to competitively inhibit Ras-dependent adenylyl cyclase activity and found to be comparable with those of yeast adenylyl cyclase and human Raf-1, with a dissociation constant (Kd) of about 1 nM. Furthermore, Byr2 inhibited a Ras GTPase-activating activity of Ira2, a S. cerevisiae homologue of neurofibromin. These results indicate that Byr2 is an immediate downstream target of Ras1 in S. pombe"
Keywords:		Adenylyl Cyclases/metabolism Enzyme Activation Fungal Proteins/metabolism/*physiology GTPase-Activating Proteins Guanosine Triphosphate/metabolism Protein Kinases/*physiology Protein Serine-Threonine Kinases/metabolism Proteins/metabolism Proto-Oncogene P;
Notes:		"MedlineMasuda, T Kariya, K Shinkai, M Okada, T Kataoka, T eng Research Support, Non-U.S. Gov't 1995/02/03 J Biol Chem. 1995 Feb 3; 270(5):1979-82. doi: 10.1074/jbc.270.5.1979"