Organization of the Ly-5 gene.
A single Ly-5 gene is known to generate a variety of transmembrane glycoprotein isoforms that distinguish various cell lineages and stages of differentiation within the hematopoietic developmental compartment of the mouse. Systems homologous to Ly-5 are known in rats and in humans. The complete exon-intron organization of the Ly-5 gene is described in this report. The Ly-5 gene occupies about 120 kilobases of chromosome 1 and comprises 34 exons, of which 32 (Ex-3 to Ex-34) are protein coding. Ex-1, Ex-2, and parts of Ex-3 and Ex-34 are untranslated. In all cDNA clones examined, either Ex-1 or Ex-2 was represented, but not both, implying that Ex-1 and Ex-2 in Ly-5 mRNA may be mutually exclusive. Primer extension and S1 nuclease protection mapping were used to identify initiation (cap) sites for transcription. The finding of putative cap sites for Ex-1 and Ex-2, and of corresponding TATA-like sequences, suggests the presence of two promoters. In both Ex-1+ and Ex-2+ cDNA clones the next exon is Ex-3, which has a translation-initiating codon. The intron between Ex-3 and Ex-4 is unusually long, about 50 kilobases. Evidence is given that Ex-5, like Ex-6 and Ex-7 (studied previously), is another alternative exon that is selectively programmed, alone or together with Ex-6 or Ex-7 or both, to generate actual or potential Ly-5 isoforms by alternative splicing.
Saga
Y
Y
Memorial Sloan-Kettering Cancer Center, New York, New York 10021.
Tung
J S
JS
Shen
F W
FW
Pancoast
T C
TC
Boyse
E A
EA
D000818:Animals; D000950:Antigens, Ly / Q000235:genetics*; D001483:Base Sequence; D004247:DNA / Q000235:genetics; D005091:Exons; D007438:Introns; D051379:Mice; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D014158:Transcription, Genetic
D000950:Antigens, Ly; D004247:DNA