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PMID: 14593073 Published · ppublish English Journal Article Research Support, U.S. Gov't, P.H.S.

Receptor internalization in yeast requires the Tor2-Rho1 signaling pathway.

Molecular biology of the cell ·Vol. 14 ·No. 11 ·2003-11-00 ·Pages 4676-84

deHart AK, Schnell JD, Allen DA, Tsai JY, Hicke L

Abstract

Efficient internalization of proteins from the cell surface is essential for regulating cell growth and differentiation. In a screen for yeast mutants defective in ligand-stimulated internalization of the alpha-factor receptor, we identified a mutant allele of TOR2, tor2G2128R. Tor proteins are known to function in translation initiation and nutrient sensing and are required for cell cycle progression through G1. Yeast Tor2 has an additional role in regulating the integrity of the cell wall by activating the Rho1 guanine nucleotide exchange factor Rom2. The endocytic defect in tor2G2128R cells is due to disruption of this Tor2 unique function. Other proteins important for cell integrity, Rom2 and the cell integrity sensor Wsc1, are also required for efficient endocytosis. A rho1 mutant specifically defective in activation of the glucan synthase Fks1/2 does not internalize alpha-factor efficiently, and fks1Delta cells exhibit a similar phenotype. Removal of the cell wall does not inhibit internalization, suggesting that the function of Rho1 and Fks1 in endocytosis is not through cell wall synthesis or structural integrity. These findings reveal a novel function for the Tor2-Rho1 pathway in controlling endocytosis in yeast, a function that is mediated in part through the plasma membrane protein Fks1.

MeSH Terms
Cell Cycle Proteins Cell Differentiation Cell Membrane/metabolism,physiology Cell Wall/metabolism,physiology Cloning, Molecular DNA-Binding Proteins/metabolism,physiology Endocytosis/physiology G1 Phase Guanine Nucleotide Exchange Factors Mutation Phosphatidylinositol 3-Kinases Phosphotransferases (Alcohol Group Acceptor)/metabolism,physiology Protein Biosynthesis Saccharomyces cerevisiae/metabolism,physiology Saccharomyces cerevisiae Proteins Signal Transduction rho GTP-Binding Proteins/metabolism,physiology
Chemicals
Cell Cycle Proteins DNA-Binding Proteins Guanine Nucleotide Exchange Factors ROM2 protein, S cerevisiae Saccharomyces cerevisiae Proteins Phosphotransferases (Alcohol Group Acceptor) TOR2 protein, S cerevisiae RHO1 protein, S cerevisiae rho GTP-Binding Proteins
Authors & Affiliations
5 authors, click to expand affiliations / ORCID
deHart Amy K A
Department of Biochemistry, Molecular Biology and Cell Biology Northwestern University, Evanston, Illinois 60208, USA.
Schnell Joshua D
Allen Damian A
Tsai Ju-Yun
Hicke Linda
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Article Info
Journal
Molecular biology of the cell
Abbr.
Mol Biol Cell
ISSN
1059-1524
DOI
10.1091/mbc.e03-05-0323
Published
2003-11-00
Pages
4676-84
Language
English
Region
United States
NLM ID
9201390
PMCID
PMC266782
Subset
IM
Grants
NIDDK NIH HHS · R01 DK053257 · United States
NIDDK NIH HHS · DK-53257 · United States
External Links
PubMed source DOI: 10.1091/mbc.e03-05-0323 PMC Full Text View journal details
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