Evolution of the neuron-specific alternative splicing product of the c-src proto-oncogene.
The observation of a slower migrating form of pp60c-src in neural tissue of chicken and mouse has recently been shown to be due to an alternative transcript form of the c-src gene (Martinez et al.: Science 237:411-415, 1987; Levy et al.: Mol Cell Biol 7:4142-4145, 1987). An insertion of 18 basepairs between exons 3 and 4, presumed to be due to alternative splicing of a mini-exon, gives rise to six amino acid residues not found in the non-neuronal (termed fibroblastic) form of pp60c-src. We have addressed the question of the evolutionary origin of the c-src neuronal insert and its functional significance regarding neural-specific expression of the c-src gene. To this end we have investigated whether the c-src gene of a lower vertebrate (the teleost fish Xiphophorus) gives rise to a neural-specific transcript in an analogous manner. We could show that the fish c-src gene does encode for a "fibroblastic" and a "neuronal" form of transcript and that the neuronal transcript does indeed arise by way of alternative splicing of a mini-exon. The mini-exon is also 18 basepairs long and we could demonstrate directly that this exon lies within the intron separating exons 3 and 4. For comparative purposes we have examined whether the fish c-yes gene, the member of the src gene family most closely related to c-src, also encodes a neural tissue-specific transcript. No evidence for a second transcript form in brain was obtained.(ABSTRACT TRUNCATED AT 250 WORDS)
Raulf
F
F
Genecenter, Max-Planck-Institute for Biochemistry, Munich-Martinsried, Federal Republic of Germany.
Robertson
S M
SM
Schartl
M
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D001923:Brain Chemistry; D002478:Cells, Cultured; D004247:DNA / Q000302:isolation & purification; D004251:DNA Transposable Elements / Q000235:genetics*; D004274:DNA, Recombinant; D005091:Exons / Q000235:genetics; D005399:Fishes / Q000235:genetics; D005784:Gene Amplification; D006829:Hydra / Q000235:genetics; D008969:Molecular Sequence Data; D009474:Neurons / Q000032:analysis*; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D016392:Proto-Oncogene Proteins pp60(c-src); D012313:RNA / Q000302:isolation & purification; D012326:RNA Splicing; D012333:RNA, Messenger / Q000032:analysis; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
D004251:DNA Transposable Elements; D004274:DNA, Recombinant; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D012313:RNA; D004247:DNA; D016392:Proto-Oncogene Proteins pp60(c-src)