Adaptor protein Ste50p links the Ste11p MEKK to the HOG pathway through plasma membrane association.
In a variety of yeast cellular pathways, the Ste50p protein regulates the kinase function of the mitogen extracellular signal-regulated kinase kinase (MEKK) Ste11p. Both Ste11p and Ste50p contain sterile alpha motif (SAM) domains; these are interchangeable, and can be replaced by other protein-interacting modules. Furthermore, the function of the Ras association (RA)-like domain of Ste50p can be mimicked by a plasma membrane recruiting signal, and direct plasma membrane targeting of Ste11p bypasses the requirement of Ste50p for Ste11p function. Thus the regulatory role of Ste50p requires both the N-terminal SAM domain to bind Ste11p and the C-terminal RA-like domain to direct kinase localization. We have identified Opy2p, an integral membrane protein that can interact with Ste50p, as a new component in the Sho1p-Ste11p/Ste50p signaling branch of the high-osmolarity glycerol (HOG) pathway. We propose that Opy2p can serve as a membrane anchor for the Ste50p/Ste11p module in the activation of the HOG pathway.
Wu
Cunle
C
Biotechnology Research Institute, Montreal, Quebec, Canada H4P 2R2. cunle.wu@cnrc-nrc.gc.ca
Jansen
Gregor
G
Zhang
Jianchun
J
Thomas
David Y
DY
Whiteway
Malcolm
M
D002462:Cell Membrane / Q000378:metabolism; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011485:Protein Binding; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism*
C079506:STE50 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D020930:MAP Kinase Kinase Kinases; C067018:Ste11 protein, S cerevisiae