Abstract
In C. elegans, a Wnt/WG-like signaling pathway down-regulates the TCF/LEF-related protein, POP-1, to specify posterior cell fates. Effectors of this signaling pathway include a beta-catenin homolog, WRM-1, and a conserved protein kinase, LIT-1. WRM-1 and LIT-1 form a kinase complex that can directly phosphorylate POP-1, but how signaling activates WRM-1/LIT-1 kinase is not yet known. Here we show that mom-4, a genetically defined effector of polarity signaling, encodes a MAP kinase kinase kinase-related protein that stimulates the WRM-1/LIT-1-dependent phosphorylation of POP-1. LIT-1 kinase activity requires a conserved residue analogous to an activating phosphorylation site in other kinases, including MAP kinases. These findings suggest that anterior/posterior polarity signaling in C. elegans may involve a MAP kinase-like signaling mechanism.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Sequence
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Animals
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Body Patterning
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Caenorhabditis elegans / embryology*
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Caenorhabditis elegans / genetics*
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Caenorhabditis elegans Proteins*
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Conserved Sequence
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Cytoskeletal Proteins / metabolism*
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DNA-Binding Proteins / chemistry
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DNA-Binding Proteins / metabolism*
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Embryo, Nonmammalian / physiology*
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Endoderm / physiology
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Enzyme Activation
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Helminth Proteins / metabolism
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High Mobility Group Proteins / chemistry
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High Mobility Group Proteins / metabolism*
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Membrane Proteins / chemistry
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Membrane Proteins / genetics*
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Membrane Proteins / metabolism*
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Molecular Sequence Data
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Phosphorylation
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Protein Serine-Threonine Kinases / metabolism*
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Sequence Alignment
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Sequence Homology, Amino Acid
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Signal Transduction
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Transcription Factors / metabolism
Substances
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Caenorhabditis elegans Proteins
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Cytoskeletal Proteins
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DNA-Binding Proteins
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Helminth Proteins
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High Mobility Group Proteins
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Membrane Proteins
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Transcription Factors
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WRM-1 protein, C elegans
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mom-4 protein, C elegans
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pop-1 protein, C elegans
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Protein Serine-Threonine Kinases
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lit-1 protein, C elegans