Caenorhabditis elegans sex-determining protein FEM-2 is a protein phosphatase that promotes male development and interacts directly with FEM-3.
Male sexual development in the nematode Caenorhabditis elegans requires the genes fem-1, fem-2, and fem-3. The current model of sex determination portrays the FEM proteins as components of a novel signal transduction pathway, but the mechanisms involved in signaling through the pathway are not understood. We report the isolation of fem-2 cDNAs in a yeast two-hybrid screen for clones encoding proteins that interact with FEM-3. Association of FEM-3 and FEM-2 in two independent in vitro binding assays substantiates the interaction detected in the two-hybrid system. FEM-2 is related in sequence to protein serine/threonine phosphatases of Type 2C (PP2C). We demonstrate that FEM-2 exhibits magnesium-dependent casein phosphatase activity, typical of PP2C, in vitro. Point mutations that abolish the casein phosphatase activity of FEM-2 without affecting its FEM-3-binding activity reduce severely its ability to rescue male development in fem-2 mutant nematodes. These results suggest that protein phosphorylation regulates sex determination in C. elegans.
Chin-Sang
I D
ID
Department of Molecular and Medical Genetics, University of Toronto, Ontario, Canada.
Spence
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AM
D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans / Q000201:enzymology* / Q000502:physiology; D029742:Caenorhabditis elegans Proteins; D004789:Enzyme Activation / Q000235:genetics; D015801:Helminth Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D006822:Hybrid Cells; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D010749:Phosphoprotein Phosphatases / Q000737:chemistry / Q000378:metabolism; D054648:Protein Phosphatase 2; D000071636:Protein Phosphatase 2C; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D012733:Sex Differentiation / Q000235:genetics*; D015003:Yeasts / Q000235:genetics
D029742:Caenorhabditis elegans Proteins; D015801:Helminth Proteins; D029701:Saccharomyces cerevisiae Proteins; C075059:fem-3 protein, C elegans; C097435:Fem-2 protein, C elegans; C087358:PTC1 protein, S cerevisiae; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2; D000071636:Protein Phosphatase 2C