Avian cellular homolog of the qin oncogene.

We have isolated chicken cDNA clones of the c-qin gene, the cellular counterpart of the v-qin (Chinese for "avian") oncogene of avian sarcoma virus 31. There are several differences between the cellular and the viral qin sequences: (i) two nonconservative amino acid substitutions in the Qin coding region; (ii) a truncation in the carboxyl terminus 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 the viral Gag domain. We have also characterized the expression pattern of c-qin in chicken embryos by in situ hybridization and by Northern blot analysis. c-qin is abundantly expressed in the developing brain, and this expression is restricted to the telencephalon of early embryos.