Structure and expression of a murine homologue of sky receptor tyrosine kinase gene.
To identify new receptor tyrosine kinases (RTKs), we screened cDNAs from mouse mammary tumor cells and mouse brain. A homology search of the complete cDNA sequences obtained showed that one cDNA was a murine homologue of recently reported human sky [Ohashi, K. et al. (1994) Oncogene 9, 699-705]. Another cDNA obtained was also related to sky but had a 5' upstream sequence similar to brt [Fujimoto, J. and Yamamoto, T. (1994) Oncogene 9, 693-698]. Analysis of the 5' region of the sky genomic DNA revealed that brt-type and sky-type sequences are encoded by the sky gene in different exons. The upstream region of the sky-type coding exon is highly GC-rich and contains potential recognition sites for the Sp1 trans-acting factor, but lacks TATA and CAAT boxes, features commonly found in promoters of other RTKs. To examine whether this upstream region functions as a promoter, we fused it with chloramphenicol acetyltransferase (CAT) gene and transfected the construct into COS-7 cells. The results of the CAT assay showed that the sky upstream region retains a significant promoter activity. Furthermore, primer extension analysis revealed that the transcription starts at -240 nt upstream from the sky translation initiation codon. These observations suggest that the brt- and sky-types of mRNA are transcribed from a single sky gene by an alternative promoter usage.
Research Laboratory, Zenyaku Kogyo Co., Ltd., Tokyo.
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Sasaki
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Enami
D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000201:enzymology; D019556:COS Cells; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D005091:Exons; D005260:Female; D015870:Gene Expression; D006801:Humans; D008325:Mammary Neoplasms, Experimental / Q000201:enzymology / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000737:chemistry* / Q000235:genetics*; D015183:Restriction Mapping; D014162:Transfection
D017931:DNA Primers; D018076:DNA, Complementary; D012333:RNA, Messenger; D015500:Chloramphenicol O-Acetyltransferase; D020794:Receptor Protein-Tyrosine Kinases; C084944:TYRO3 protein, human