CLONING AND CHARACTERIZATION OF E2F-2, A NOVEL PROTEIN WITH THE BIOCHEMICAL-PROPERTIES OF TRANSCRIPTION FACTOR-E2F

E2F is a mammalian transcription factor that appears to play an import ant role in cell cycle regulation. While at least two proteins (E2F-1 and DP-1) with E2F-like activity have been cloned, studies from severa l laboratories suggest that additional homologs may exist. A novel pro tein with E2F-like properties, designated E2F-2, was cloned by screeni ng a HeLa cDNA library with a DNA probe derived from the DNA binding d omain of E2F-1 (K. Helin, J. A. Lees, M. Vidal, N. Dyson, E. Harlow, a nd A. Fattaey, Cell 70:337-350, 1992). E2F-2 exhibits overall 46% amin o acid identity to E2F-1. Both the sequence and the function of the DN A and retinoblastoma gene product binding domains of E2F-1 are conserv ed in E2F-2. The DNA binding activity of E2F-2 is dramatically enhance d by complementation with particular sodium dodecyl sulfate-polyacryla mide gel electrophoresis-purified components of HeLa cell E2F, and ant i-E2F-2 antibodies cross-react with components of purified HeLa cell E 2F. These observations are consistent with a model in which E2F binds DNA as a heterodimer of two distinct proteins, and E2F-2 is functional ly and immunologically related to one of these proteins.