INACTIVATION OF ONCOPROTEIN BINDING BY A SINGLE CYS(706)-TO-TYR SUBSTITUTION IN THE RETINOBLASTOMA PROTEIN

We previously found a new single amino acid substitution at codon 706 (Cys-to-Sr) of the retinoblastoma (RB) gene in a sporadic retinoblasto ma patient. The glutathione S-transferase-RB fused protein containing this mutation was here tested for binding to SV40 large T antigen and adenovirus EIA protein, and was shown to have lost its binding affinit y. Thus, Tyr, as well as Phe, residues substituted for Cys(706) were f ound to abolish the RB protein activity.