A Domain Responsible for the Transformation Suppressor Activity in Krev‐1 Protein

Krev-1 cDNA encodes a ras-related protein and exhibits an activity of inducing flat revertants at certain frequencies (2-5% of total transfectants) when introduced into a v-K-ras-transformed mouse NIH3T3 cell line, DT. To explore the functional organization of Krev-1 protein, we constructed a series of chimeric genes consisting of fragments of H-ras and Krev-1 cDNAs, and tested their biological activities in DT cells. The results indicated that the determinant for the transformation suppressor activity resides in the N-terminal one-third of the Krev-1 encoded polypeptide within which a highly conserved, putative effector-binding domain is present.