In the free-living ciliate Euplotes raikovi, we identified (and designated as Er-MAPK1) a protein kinase of 631 amino acids, that appears to be constantly phosphorylated in cells which are in growth stage and interact in autocrine fashion with their water-soluble signal pheromones. Er-MAPK1 is specified by a gene that requires aþ1 translational frame-shift to be expressed. Its amino-terminal region represents a canonical catalytic domain and carries an activation loop distinctive of the mitogenactivated protein kinases, with the Thr-Asp-Tyr motif deputed to be site of double phosphorylation. In contrast, the carboxy-terminal region appears to be structurally unique. It shows a strongly basic amino acid composition, is very rich in glycine repetitions, and contains a bipartite signal for translocation of Er-MAPK1 into the nucleus.

A Novel Protein Kinase from the Ciliate Euplotes raikovi with Close Structural Identity to the Mammalian Intestinal and Male-Germ Cell Kinases: Characterization and Functional Implications in the Autocrine Pheromone Signaling Loop

VALLESI, Adriana;BALLARINI, Patrizia;LUPORINI, Pierangelo
2010-01-01

Abstract

In the free-living ciliate Euplotes raikovi, we identified (and designated as Er-MAPK1) a protein kinase of 631 amino acids, that appears to be constantly phosphorylated in cells which are in growth stage and interact in autocrine fashion with their water-soluble signal pheromones. Er-MAPK1 is specified by a gene that requires aþ1 translational frame-shift to be expressed. Its amino-terminal region represents a canonical catalytic domain and carries an activation loop distinctive of the mitogenactivated protein kinases, with the Thr-Asp-Tyr motif deputed to be site of double phosphorylation. In contrast, the carboxy-terminal region appears to be structurally unique. It shows a strongly basic amino acid composition, is very rich in glycine repetitions, and contains a bipartite signal for translocation of Er-MAPK1 into the nucleus.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11581/102710
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