title: P-57 is a neural specific calmodulin-binding protein.
abstract: P-57 is a novel calmodulin-binding protein which has recently been isolated from bovine cerebral cortex (Andreasen, T. J., Luetje, C. W., Heideman, W., and Storm, D. R. (1983) Biochemistry 22, 4615-4618). In contrast to all other calmodulin-binding proteins characterized thus far, P-57 has equivalent or higher affinity for calmodulin in the absence of free Ca2+ compared to the presence of Ca2+. In this study, the distribution of P-57 in other tissues and within brain was examined using a radioimmune assay and photoaffinity labeling with azido-125I-calmodulin. P-57 was not found in tissues other than brain, retina, and spinal cord. Within brain, P-57 levels varied from 0.1% of the total protein in white matter regions to about 0.5% in cell body-rich fractions. The protein was found in both membrane and soluble fractions. P-57 is the most abundant calmodulin-binding protein in brain and appears to be neural specific. The concentrations of P-57 in brain and its affinity for calmodulin in the absence of Ca2+ are sufficient to complex a significant fraction of the total calmodulin present.
authors.forename: B M
authors.initials: BM
authors.lastname: Cimler
authors.forename: T J
authors.initials: TJ
authors.lastname: Andreasen
authors.forename: K I
authors.initials: KI
authors.lastname: Andreasen
authors.forename: D R
authors.initials: DR
authors.lastname: Storm
mesh_terms: D000818:Animals; D000906:Antibodies; D000936:Antigen-Antibody Complex; D001921:Brain / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology; D002148:Calmodulin-Binding Proteins; D002417:Cattle; D002540:Cerebral Cortex / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D010749:Phosphoprotein Phosphatases / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D011863:Radioimmunoassay; D014018:Tissue Distribution
chemical_list: D000906:Antibodies; D000936:Antigen-Antibody Complex; D002148:Calmodulin-Binding Proteins; D010749:Phosphoprotein Phosphatases; D002118:Calcium