Published online
doi:10.1083/jcb.200704079
The Journal of Cell Biology, Vol. 181, No. 7, 1073-1081
The Rockefeller University Press, 0021-9525 $30.00
© Vadaie et al.
Cleavage of the signaling mucin Msb2 by the aspartyl protease Yps1 is required for MAPK activation in yeast
Nadia Vadaie1,
Heather Dionne1,
Darowan S. Akajagbor1,
Seth R. Nickerson1,
Damian J. Krysan2, and
Paul J. Cullen1
1 Department of Biological Sciences, State University of New York at Buffalo, Buffalo, NY 14260
2 Department of Pediatrics, University of Rochester Medical Center, Rochester NY 14642
Correspondence to Paul J. Cullen: pjcullen{at}buffalo.edu
Signaling mucins are cell adhesion molecules that activate RAS/RHO guanosine triphosphatases and their effector mitogen-activated protein kinase (MAPK) pathways. We found that the Saccharomyces cerevisiae mucin Msb2p, which functions at the head of the Cdc42p-dependent MAPK pathway that controls filamentous growth, is processed into secreted and cell-associated forms. Cleavage of the extracellular inhibitory domain of Msb2p by the aspartyl protease Yps1p generated the active form of the protein by a mechanism incorporating cellular nutritional status. Activated Msb2p functioned through the tetraspan protein Sho1p to induce MAPK activation as well as cell polarization, which involved the Cdc42p guanine nucleotide exchange factor Cdc24p. We postulate that cleavage-dependent activation is a general feature of signaling mucins, which brings to light a novel regulatory aspect of this class of signaling adhesion molecule.
Abbreviations used in this paper: CD, cleavage domain; co-IPT, coimmunoprecipitation; GEF, guanine nucleotide exchange factor; HOG, high osmolarity glycerol response; MHD, mucin homology domain; TM, transmembrane; WT, wild type.
© 2008 Vadaie et al. This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.jcb.org/misc/terms.shtml). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/).

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