Structure and expression of the human L-myc gene reveal a complex pattern of alternative mRNA processing.
We analyzed in detail the structure of the L-myc gene isolated from human placental DNA and characterized its expression in several small-cell lung cancer cell lines. The gene is composed of three exons and two introns spanning 6.6 kilobases in human DNA. Several distinct mRNA species are produced in all small-cell lung cancer cell lines that express L-myc. These transcripts are generated from a single gene by alternative splicing of introns 1 and 2 and by use of alternative polyadenylation signals. In some mRNAs there is a long open reading frame with a predicted translated protein of 364 residues. Amino acid sequence comparison with c-myc and N-myc demonstrated multiple discrete regions with extensive homology. In contrast, other mRNA transcripts, generated by alternative processing, could encode a truncated protein with a novel carboxy-terminal end.
Kaye
F
F
NCI-Navy Medical Oncology Branch, Naval Hospital, Bethesda, Maryland.
Battey
J
J
Nau
M
M
Brooks
B
B
Seifter
E
E
De Greve
J
J
Birrer
M
M
Sausville
E
E
Minna
J
J
D000595:Amino Acid Sequence; D001483:Base Sequence; D018288:Carcinoma, Small Cell / Q000235:genetics; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D005796:Genes; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics; D008969:Molecular Sequence Data; D005810:Multigene Family; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D011519:Proto-Oncogenes; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000235:genetics*; D014158:Transcription, Genetic
D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D004247:DNA