Homology between the DNA-binding domain of the GCN4 regulatory protein of yeast and the carboxyl-terminal region of a protein coded for by the oncogene jun.

The product of the recently described oncogene jun shows significant amino acid sequence homology with the GCN4 yeast transcriptional activator protein. The similarity is restricted to the 66 carboxyl-terminal amino acids, thought to be the DNA-binding domain of the GCN4 protein. In these alpha-helix-permissive regions of the jun and GCN4 products there is also a lesser but still significant amino acid resemblance to the fos protein and a marginal degree of similarity to myc proteins. The amino acid sequence homology between GCN4 and jun gene products suggests that the jun protein may bind to DNA in a sequence-specific way and exert a regulatory function.