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.