title: A radioimmunoassay for the phosphoprotein B-50: distribution in rat brain.
abstract: A radioimmunoassay (RIA) for the B-50 protein was developed to determine B-50 in total homogenates of rat tissues. A tracer of purified B-50 was prepared at high activity (10-30 microCi/micrograms protein) by phosphorylating B-50 with carrier-free [gamma-32P]ATP, catalyzed by purified protein kinase C. The RIA was performed using affinity-purified anti-B-50 immunoglobulins G in a detergent containing medium and detected B-50 at levels of 0.1-10 ng. Specificity of the antibodies was ascertained by immunoprecipitation of B-50 from a crude mitochondrial membrane fraction from rat brain and by immunoblotting. For the B-50 content in rat brain the following distribution pattern was found: medulla spinalis less than cerebellum less than hippocampus; cerebral cortex less than periaqueductal gray less than septum. The septum contained 80 micrograms/g tissue weight. The level in liver homogenates was below detection. The regional distribution is in fair agreement with the pattern of the endogenous B-50 phosphorylation in rat brain synaptosomal plasma membranes previously reported.
mesh_terms: D000818:Animals; D001923:Brain Chemistry; D002531:Cerebellum / Q000032:analysis; D002540:Cerebral Cortex / Q000032:analysis; D019922:GAP-43 Protein; D006624:Hippocampus / Q000032:analysis; D008297:Male; D010487:Periaqueductal Gray / Q000032:analysis; D010750:Phosphoproteins / Q000032:analysis* / Q000378:metabolism; D010766:Phosphorylation; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D012688:Septum Pellucidum / Q000032:analysis; D013116:Spinal Cord / Q000032:analysis; D013570:Synaptic Membranes; D014018:Tissue Distribution
chemical_list: D019922:GAP-43 Protein; D010750:Phosphoproteins