E2F-4 and E2F-5, two members of the E2F family, are expressed in the early phases of the cell cycle

Proc Natl Acad Sci U S A. 1995 Mar 14;92(6):2403-7. doi: 10.1073/pnas.92.6.2403.


The E2F transcription factors play a role in regulating the expression of genes required for cell proliferation. Their activity appears to be regulated by association with the retinoblastoma protein (pRb) and the pRb-related proteins p107 and p130. In vivo, pRb is found in complex with a subset of E2F components--namely, E2F-1, E2F-2, and E2F-3. Here we describe the characterization of cDNAs encoding two unusual E2Fs, E2F-4 and E2F-5, each identified by the ability of their gene product to interact with p130 in a yeast two-hybrid system. E2F-4 and -5 share common sequences with E2F-1, E2F-2, and E2F-3 and, like these other E2Fs, the ability to heterodimerize with DP-1, thereby acquiring the ability to bind an E2F DNA recognition sequence with high affinity. However, in contrast to E2F-1, E2F-4 and E2F-5 fail to bind pRb in a two-hybrid assay. Moreover, they show a unique pattern of expression in synchronized human keratinocytes: E2F-4 and E2F-5 mRNA expression is maximal in mid-G1 phase before E2F-1 expression is detectable. These findings suggest that E2F-4 and E2F-5 may contribute to the regulation of early G1 events including the G0/G1 transition.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Biological Evolution*
  • Cell Cycle*
  • Cell Line
  • Cloning, Molecular
  • DNA, Complementary
  • DNA-Binding Proteins / biosynthesis*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Drosophila
  • E2F4 Transcription Factor
  • E2F5 Transcription Factor
  • Fibroblasts
  • Gene Expression Regulation
  • Gene Expression*
  • Gene Library
  • Humans
  • Keratinocytes / metabolism*
  • Kinetics
  • Molecular Sequence Data
  • Phylogeny
  • Plasmids
  • RNA, Messenger / analysis
  • RNA, Messenger / biosynthesis
  • RNA, Messenger / isolation & purification
  • RNA, Messenger / metabolism
  • Saccharomyces cerevisiae
  • Sequence Homology, Amino Acid
  • Transcription Factors / biosynthesis*
  • Transcription Factors / genetics
  • Transcription Factors / metabolism


  • DNA, Complementary
  • DNA-Binding Proteins
  • E2F4 Transcription Factor
  • E2F5 Transcription Factor
  • E2F5 protein, human
  • RNA, Messenger
  • Transcription Factors

Associated data

  • GENBANK/U15641
  • GENBANK/U15642