Transformation by Rous sarcoma virus induces a novel gene with homology to a mitogenic platelet protein.

A cDNA clone, designated 9E3, was isolated from a chick embryo fibroblast (CEF) cDNA library. 9E3 mRNA was 20-fold higher in CEF following transformation by Rous sarcoma virus because of increased transcription rate. In CEF infected with temperature-sensitive mutants, increased 9E3 mRNA was found within 2 hr of a shift to permissive temperature. Nucleotide sequence and in vitro translation results indicate that 9E3 mRNA encodes an 11 kd polypeptide that is homologous to human connective tissue activating peptide III (CTAP-III), a mitogenic platelet alpha-granule protein, and to beta-thromboglobulin and platelet factor 4. The reported biological activities of CTAP-III suggest that elevated expression of 9E3 may play a role in producing some of the phenotypic features of RSV-transformed cells.