Re-examination of the post-translational arginylated protein of 125-kD initially identified as N-STOP.
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.
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.
María Belén
MB
Decca
Mauricio R
MR
Galiano
Héctor S
HS
Barra
Marta E
ME
Hallak
D000818:Animals; D001120:Arginine / Q000378:metabolism*; D001921:Brain / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism; D002845:Chromatography; D015180:Electrophoresis, Gel, Two-Dimensional; D051379:Mice; D018345:Mice, Knockout; D008869:Microtubule-Associated Proteins / Q000737:chemistry / Q000172:deficiency / Q000378:metabolism; D008970:Molecular Weight; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D051381:Rats; D014020:Tissue Extracts / Q000378:metabolism
D002147:Calmodulin; C113727:Map6 protein, rat; D008869:Microtubule-Associated Proteins; C491893:Mtap6 protein, mouse; D009419:Nerve Tissue Proteins; D014020:Tissue Extracts; D001120:Arginine; D002118:Calcium