title: pp60c-src is expressed in human fetal and adult brain.
abstract: Human cells contain a tyrosine-specific protein kinase, pp60c-src, that is highly homologous to the oncogene product, pp60v-src, from Rous sarcoma virus but is of unknown function. The expression of human pp60c-src was examined in tissues obtained from human adults and fetuses of 20-32 weeks' gestational age. pp60c-src was quantitated in tissue extracts by measurement of its protein kinase activity by the use of the immune complex protein kinase assay. Brain showed the highest levels of pp60c-src protein kinase activity, but all other human tissues examined had significant levels. Fetal tissues, including brain, showed three- to eight-fold higher levels of pp60c-src kinase activity than the corresponding adult tissues. pp60c-src kinase was found to be uniformly distributed in the adult brain; frontal, occipital, and parietal cortex, and cerebellum expressed equivalent amounts of pp60c-src kinase activity. The protein kinase activity in human tissues exhibited properties characteristic of pp60c-src in other species, namely, tyrosine-specific phosphorylation of specific antibody heavy chains, autophosphorylation of a 60,000 Mr protein following immunoprecipitation with a monoclonal antibody specific for pp60src, and sensitivity to inhibition by P1,P4-di(adenosine-5')tetraphosphate. The high levels of human pp60c-src in fetal tissues, particularly in brain, suggest a possible function in developmental processes.
authors.forename: J P
authors.initials: JP
authors.lastname: Sorge
authors.forename: L K
authors.initials: LK
authors.lastname: Sorge
authors.forename: P F
authors.initials: PF
authors.lastname: Maness
mesh_terms: D000227:Adenine Nucleotides / Q000494:pharmacology; D000911:Antibodies, Monoclonal / Q000276:immunology; D001921:Brain / Q000196:embryology / Q000201:enzymology*; D002531:Cerebellum / Q000196:embryology / Q000201:enzymology; D015226:Dinucleoside Phosphates; D005333:Fetus / Q000378:metabolism*; D006321:Heart / Q000196:embryology; D006801:Humans; D007118:Immunoassay; D008099:Liver / Q000196:embryology / Q000201:enzymology; D009132:Muscles / Q000196:embryology / Q000201:enzymology; D009206:Myocardium / Q000201:enzymology; D010750:Phosphoproteins / Q000096:biosynthesis*; D010766:Phosphorylation; D016392:Proto-Oncogene Proteins pp60(c-src); D013116:Spinal Cord / Q000196:embryology / Q000201:enzymology
chemical_list: D000227:Adenine Nucleotides; D000911:Antibodies, Monoclonal; D015226:Dinucleoside Phosphates; D010750:Phosphoproteins; C020733:diadenosine tetraphosphate; D016392:Proto-Oncogene Proteins pp60(c-src)