Structure of the murine c-sis proto-oncogene (Sis, PDGFB) encoding the B chain of platelet-derived growth factor

The murine proto-oncogene c-sis (Sis, PDGFB), encoding the B chain of platelet-derived growth factor, has been cloned. Its structure, with seven exons spanning approximately 20 kb, closely resembles that of the human and feline homologs. The predicted amino acid sequence of murine PDGF-B has residues 89% identical to those of human PDGF-B. A noncoding region at the start of exon 7, which is deleted by alternative splicing during the generation of the viral v-sis oncogene, is highly conserved in human, mouse, and cat and may represent an important regulatory element.