title: Tyrosine protein kinases in membrane fractions from rat cerebral cortex.
abstract: Specific activities of tyrosine tubulin kinase in the particulate fractions from rat cerebellum, medulla oblongata, hypothalamus, striatum, midbrain, and cerebral cortex ranged within 30% of each other and more than 3 times higher than those in the soluble fractions. In the cerebral cortex, tyrosine protein kinase activity toward tubulin and tyrosine-glutamate (1:4) copolymers was mainly distributed in the plasma membrane and the microsome fractions. The kinase activity in cerebral cortex particulate fractions was quantitatively solubilized and separated into two peaks, kinase I and kinase II, by Sephacryl S-300 gel filtration in the presence of 0.2% Nonidet P-40 and 0.2 M NaCl. Kinases I and II were each resolved into 5 active peaks (I-1----5 and II-1----5) by casein-Sepharose column chromatography. The molecular weights of these kinases were estimated from the s20,w values to be 59,000-65,000. The Km values of II-1----5 for tubulin were nearly 10 times higher than those of I-1----5. However, the Km values of the two groups of kinases for tyrosine-glutamate copolymers were not so significantly different. About 60% of the copolymers kinase activity in I-3, I-4, II-3, and II-4 was immunoprecipitable with a saturating amount of monoclonal antibody against pp60c-src. Incubation of the immunoprecipitates with ATP resulted in the autophosphorylation of a 60 kDa protein in I-3 and I-4, and a 52 kDa protein in II-3 and II-4. Immunoblotting also indicated I-3 and I-4 as 60 kDa bands and II-3 and II-4 as 52 kDa bands on SDS-polyacrylamide gels.(ABSTRACT TRUNCATED AT 250 WORDS)
authors: Department of Biochemistry, Hiroshima University School of Medicine.
authors: H
authors: H
authors: Tsukamoto
authors: K
authors: K
authors: Azuma
authors: T
authors: T
authors: Miyauchi
authors: H
authors: H
authors: Usui
authors: M
authors: M
authors: Takeda
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002540:Cerebral Cortex / Q000201:enzymology*; D007700:Kinetics; D008297:Male; D008970:Molecular Weight; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000276:immunology / Q000302:isolation & purification* / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000276:immunology / Q000302:isolation & purification; D016392:Proto-Oncogene Proteins pp60(c-src); D051381:Rats; D013347:Subcellular Fractions / Q000201:enzymology; D013379:Substrate Specificity
chemical_list: D011518:Proto-Oncogene Proteins; D011505:Protein-Tyrosine Kinases; D016392:Proto-Oncogene Proteins pp60(c-src)