Re-examination of the Post-translational Arginylated Protein of 125-kD Initially Identified as N-STOP |
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Authors: | María Belén Decca Mauricio R Galiano Héctor S Barra Marta E Hallak |
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Institution: | Centro de Investigaciones en Química Biológica de Córdoba, CIQUIBIC, (UNC-CONICET), Departamento de Quimica Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, 5000-Córdoba, Argentina. |
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Abstract: | Post-translational modification of proteins is a complex mechanism by which cells regulate protein activities. One post-translational modification is the incorporation of arginine into the NH2-terminus of proteins. It has been hypothesized that in rat brain extracts, one of the proteins modified by this reaction is the microtubule-associated protein Neuronal Stable Tubule Only Polypeptide (N-STOP). This was inferred from its electrophoretic mobility (125 kD) and because it was immunoprecipitated with a monoclonal antibody against the N-STOP. However, this hypothesis is not supported by our recent results. Herein, we found that rat N-STOP interacts with Ca(2+)-calmodulin, whereas the 125-kD 14C]-arginylated protein does not. The 125-kD 14C]-arginylated protein from rat brain is separated from the N-STOP by two-dimensional electrophoresis, and it is not recognized by a STOP monoclonal antibody. Mouse brain contains N-STOP, which migrates as a protein of 116 kD and could not be labeled by the post-translational incorporation of 14C]-arginine. The 125-kD 14C]-arginylated protein appears in wild-type as well as in STOP knock out mice. Based on these results, we conclude that the 125-kD arginylated protein is different from N-STOP. |
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Keywords: | Post-translational modifications arginylation STOP protein arginyl-tRNA protein transferase |
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