Serum response factor associated ETS proteins: ternary complex factors and PEA3-binding factor.

An ETS protein binding motif CAGGAT adjoins the 5' side of the Serum Response Element in the c-fos promoter. This sequence is recognized by several ETS proteins which are able to form ternary complexes in the presence of Serum Response Factor. Related sequences, capable of ternary complex formation, are also found in the promoters of immediate early zinc finger proteins. However, similar sequences found in the gamma-actin and c-ets-2 promoters could not bind Ternary Complex Factor. We purified a 60-kDa human ETS protein which could bind the sequence recognized by Ternary Complex Factor, and this protein could bind DNA in the absence of Serum Response Factor. Interestingly, this protein also binds Serum Response Factor in vitro. Therefore the Serum Response Factor DNA-binding/oligomerization domain has affinities for distinct ETS oncoproteins.