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Biochemistry

Title:		Phosphorylation of the RGS protein Sst2 by the MAP kinase Fus3 and use of Sst2 as a model to analyze determinants of substrate sequence specificity
Author(s):		Parnell SC; Marotti LA; Kiang L; Torres MP; Borchers CH; Dohlman HG;
Address:		"Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill 27599-7260, USA"
Journal Title:		Biochemistry
Year:		2005
Volume:		44
Issue:		22
Page Number:		8159 - 8166
DOI:		10.1021/bi0503091
ISSN/ISBN:		0006-2960 (Print) 0006-2960 (Linking)
Abstract:		"Previously, we used mass spectrometry to demonstrate pheromone-stimulated phosphorylation of Ser-539 in Sst2, a regulator of G protein signaling in yeast Saccharomyces cerevisiae [Garrison, T. R., et al. (1999) J. Biol. Chem. 274, 36387-36391]. Here, we show that Sst2 phosphorylation is mediated by the mitogen-activated protein (MAP) kinase Fus3. Phosphorylation occurs within a canonical MAP kinase phosphorylation site (Pro-X-Ser/Thr-Pro, where 'X' at the -1 position can be any amino acid), a consensus sequence deduced earlier from analysis of synthetic peptide substrates. In a direct test of the model, we compared Sst2 phosphorylation following systematic substitution of the -1 residue His-538. Each of the substitution mutants was suitable as a MAP kinase substrate, as shown by phosphorylation-dependent mobility shifts in vivo and/or by direct phosphorylation in vitro followed by peptide mapping and mass spectrometry sequencing. This analysis documents phosphorylation of Sst2 by Fus3 and demonstrates that the prevailing model for MAP kinase recognition is valid for a native substrate protein in vivo as well as for small synthetic peptides tested in vitro"
Keywords:		"Alanine/genetics Amino Acid Sequence Amino Acid Substitution/genetics Consensus Sequence Feedback, Physiological/genetics GTPase-Activating Proteins/chemistry/genetics/*metabolism Histidine/genetics Mitogen-Activated Protein Kinases/*chemistry/genetics Mo;"
Notes:		"MedlineParnell, Stephen C Marotti, Louis A Jr Kiang, Lee Torres, Matthew P Borchers, Christoph H Dohlman, Henrik G eng R01 GM055316/GM/NIGMS NIH HHS/ GM055316/GM/NIGMS NIH HHS/ GM059167/GM/NIGMS NIH HHS/ R01 GM059167/GM/NIGMS NIH HHS/ ES011997/ES/NIEHS NIH HHS/ Research Support, N.I.H., Extramural Research Support, U.S. Gov't, P.H.S. Validation Study 2005/06/01 Biochemistry. 2005 Jun 7; 44(22):8159-66. doi: 10.1021/bi0503091"