Structure And Function Of The Src Gene Of Rous Sarcoma Virus And The Human Cellular Src Gene

The Rous sarcoma virus (RSV) src gene (v-src) is one of that most extensively studied oncogenes, yet the mechanism by which it transforms virus-infected cells remains unsolved. The study of mutants of RSV provides considerable information on the function of the v-src protein (p60(\u27v-src)).;Characterization of the chicken cellular counterpart of the v-src gene (c-src) has provided clues as to the alterations required to produce an oncogene from a normal cellular gene (proto-oncogene). Characterization of the human c-src gene will be useful for future studies aimed at detecting possible human c-src alterations associated with human neoplastic disorders.;The nucleotide sequence of the 3\u27 three-quarters of a molecularly cloned human c-src gene was determined. This region of the c-src gene encodes the tyrosine kinase domain of p60(\u27c-src) and corresponds to exons 4 through 12 of the chicken c-src gene. Human c-src is very strongly conserved with respect to the chicken c-src gene; 90% nucleotide homology and 98% amino acid homology exists between human and chicken c-src. The exon sizes and the locations of the exon-intron boundaries are identical in human and chicken c-src. Sequences within introns are not conserved, and most of the introns of human c-src are much larger than the corresponding chicken c-src introns.;The strong amino acid conservation of this region of p60(\u27c-src) of species as divergent as humans and chickens suggests that this portion of p60(\u27c-src) specifies one or more functional domains that are of great importance to some aspect of normal cellular growth or differentiation.;The nature of the lesions in three fusiform mutants (WO101, WO201, and tsST529) of the Schmidt-Ruppin strain of RSV was determined by molecular cloning and DNA sequencing. WO101, WO201, and tsST529 all contained an in frame deletion in the v-src region coding for amino acids 116-140 of p60(\u27src). The deleted segment is flanked by consensus splice donor and acceptor sequences and contains an appropriately positioned branchpoint acceptor consensus sequence, suggesting that the deletion occurred through an aberrant RNA splicing event. These results suggest that a protein domain within the N-terminal 1/3 of p60(\u27v-src) is important for controlling morphological parameters of transformation in RSV-infected cells