An alternative non-tyrosine protein kinase product of the c-src gene in chicken skeletal muscle.
While the c-src locus is expressed as a 4.0-kilobase (kb) mRNA coding for pp60c-src in various chicken tissues, including embryonic muscle, it is expressed as a novel 3.0-kb mRNA in adult skeletal muscle. We have analyzed the primary structure of this alternatively transcribed and spliced c-src mRNA. The sequence revealed three open reading frames, with the previously defined c-src exons 1 through 5 or 6 comprising the third, on the 3' untranslated region of this 3-kb mRNA. The exons coding for the tyrosine kinase domain of pp60c-src were excluded. On the 5' side, 2 kb of sequence upstream from the previously defined exon 1 of the c-src gene was included in this mRNA. The start site for the 3-kb mRNA probably lies downstream of that for the 4-kb mRNA. The first reading frame of the 3.0-kb mRNA, called sur (for src upstream region), encoded a 24-kilodalton (kDa) protein product rich in cysteine and proline residues. In vitro analysis indicated that the 24-kDa sur protein was membrane associated. Antibodies to sur protein detected in vivo a 24-kDa muscle-specific protein which was developmentally regulated and corresponded to the switch from the 4-kb to the 3-kb c-src mRNA. A striking kinetic pattern of appearance of sur protein and disappearance of pp60c-src suggests that the expression of these two proteins is inversely related.
Dorai
T
T
Department of Microbiology, Mount Sinai School of Medicine, New York, New York 10029-6574.
Wang
L H
LH
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D002645:Chickens; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D005822:Genetic Vectors; D008969:Molecular Sequence Data; D009132:Muscles / Q000201:enzymology*; D015688:Oncogene Protein pp60(v-src) / Q000235:genetics*; D009857:Oncogenes; D014176:Protein Biosynthesis; D011494:Protein Kinases / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D015183:Restriction Mapping; D014158:Transcription, Genetic
D012333:RNA, Messenger; D004247:DNA; D011494:Protein Kinases; D015688:Oncogene Protein pp60(v-src)