Open AccessDimerization of Ste5, a mitogen-activated protein kinase cascade scaffold protein, is required for signal transduction
Author(s) -
Deborah Yablonski,
Irith Marbach,
Alexander Levitzki
Publication year - 1996
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.93.24.13864
Subject(s) - complementation , scaffold protein , signal transduction , biology , mutant , immunoprecipitation , protein kinase a , protein fragment complementation assay , kinase , microbiology and biotechnology , biochemistry , gene
The mitogen-activated protein kinase cascade of theSaccharomyces cerevisiae pheromone response pathway is organized on the Ste5 protein, which binds each of the kinases of the cascade prior to signaling. In this study, a structure–function analysis of Ste5 deletion mutants uncovered new functional domains of the Ste5 protein and revealed that Ste5 dimerizes during the course of normal signal transduction. Dimerization, mediated by two regions in the N-terminal half of Ste5, was first suggested by intragenic complementation between pairs of nonfunctional Ste5 mutants and was confirmed by using the two-hybrid system. Coimmunoprecipitation of differently tagged forms of Ste5 from cells in which the pathway has been activated by Ste5 overexpression further confirmed dimerization. A precise correlation between the biological activity of various Ste5 fragments and dimerization suggests that dimerization is essential for Ste5 function.