AVIAN CELLULAR HOMOLOG OF THE QIN ONCOGENE

We have isolated chicken cDNA clones of the c-qin gene, the cellular c ounterpart of the v-qin (Chinese for ''avian'') oncogene of avian sarc oma virus 31. There are several differences between the cellular and t he viral gin sequences: (i) two nonconservative amino acid substitutio ns in the Qin coding region; (ii) a truncation in the carboxyl terminu s of the viral protein due to a premature stop codon; (iii) a partial Gag sequence fused to the amino terminus of viral Qin; and (iv) eight cell-coded amino acids which link the cellular Qin coding domain to th e viral Gag domain. We have also characterized the expression pattern of c-qin in chicken embryos by in situ hybridization and by Northern b lot analysis. c-qin is abundantly expressed in the developing brain, a nd this expression is restricted to the telencephalon of early embryos .