Identification of reelin-induced sites of tyrosyl phosphorylation on disabled 1.
The study of mice with spontaneous and targeted mutations has uncovered a signaling pathway that controls neuronal positioning during mammalian brain development. Mice with disruptions in reelin, dab1, or both vldlr and apoER2 are ataxic, and they exhibit severe lamination defects within several brain structures. Reelin is a secreted extracellular protein that binds to the very low density lipoprotein receptor and the apolipoprotein E receptor 2 on the surface of neurons. Disabled-1 (Dab1), an intracellular adapter protein containing a PTB (phosphotyrosine binding) domain, is tyrosyl-phosphorylated during embryogenesis, but it accumulates in a hypophosphorylated form in mice lacking Reelin or both very low density lipoprotein receptor and apolipoprotein E receptor 2. Dab1 is rapidly phosphorylated when neurons isolated from embryonic brains are stimulated with Reelin, and several tyrosines have been implicated in this response. Mice with phenylalanine substitutions of all five tyrosines (Tyr(185), Tyr(198), Tyr(200), Tyr(220), and Tyr(232)) exhibit a reeler phenotype, implying that tyrosine phosphorylation is critical for Dab1 function. Here we report that, although Src can phosphorylate all five tyrosines in vitro, Tyr(198) and Tyr(220) represent the major sites of Reelin-induced Dab1 phosphorylation in embryonic neurons.
Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA.
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Keshvara
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Benhayon
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Magdaleno
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Curran
D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000254:growth & development / Q000502:physiology*; D015816:Cell Adhesion Molecules, Neuronal / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D016326:Extracellular Matrix Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000502:physiology*; D010446:Peptide Fragments / Q000737:chemistry; D010748:Phosphopeptides / Q000737:chemistry; D010750:Phosphoproteins / Q000235:genetics; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D000091042:Reelin Protein; D012697:Serine Endopeptidases; D015398:Signal Transduction
D015816:Cell Adhesion Molecules, Neuronal; C103773:Dab1 protein, mouse; D016326:Extracellular Matrix Proteins; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D010748:Phosphopeptides; D010750:Phosphoproteins; D011993:Recombinant Fusion Proteins; D000091042:Reelin Protein; D019000:Phosphotyrosine; C000717128:Reln protein, mouse; D012697:Serine Endopeptidases