Phosphorylation of a specific cdk site in E2F-1 affects its electrophoretic mobility and promotes pRB-binding in vitro.

TY - JOUR

T1 - Phosphorylation of a specific cdk site in E2F-1 affects its electrophoretic mobility and promotes pRB-binding in vitro.

AU - Peeper, D S

AU - Keblusek, P

AU - Helin, K

AU - Toebes, M

AU - van der Eb, A J

AU - Zantema, A

N1 - Keywords: Animals; Base Sequence; Carrier Proteins; Cell Cycle Proteins; Cells, Cultured; Cyclin-Dependent Kinases; DNA-Binding Proteins; E2F Transcription Factors; E2F1 Transcription Factor; Electrophoresis, Polyacrylamide Gel; Humans; Molecular Sequence Data; Oligodeoxyribonucleotides; Phosphorylation; Protein Binding; Retinoblastoma Protein; Spodoptera; Transcription Factor DP1; Transcription Factors

PY - 1995

Y1 - 1995

N2 - The E2F transcription factor family participates in growth control presumably through transcriptional activation of genes that promote entry into S phase. E2F activity is believed to be controlled across the cell cycle by association with various cellular proteins, including the product of the retinoblastoma gene (pRB). We find that E2F-1 proteins are heterogeneously phosphorylated in insect cells, as a result of which they migrate as a doublet on SDS-polyacrylamide gels. This electrophoretic shift is shown to be dependent upon specific phosphorylation of E2F-1 on serine-375 (S375), near the pRB-binding site. Phosphorylation on S375 also occurs in human cells. E2F-1 was most efficiently phosphorylated on this residue by cyclin A/cdk2 kinase, and to a lesser extent by cyclin A/cdk2, irrespective of the presence of the pRB-related p107 protein. Phosphorylation of E2F-1 on S375 greatly enhanced its affinity of pRB in vitro. These results suggest a novel way of regulating E2F-1 activity, namely by cell-cycle-dependent phosphorylation of this transcription factor.

AB - The E2F transcription factor family participates in growth control presumably through transcriptional activation of genes that promote entry into S phase. E2F activity is believed to be controlled across the cell cycle by association with various cellular proteins, including the product of the retinoblastoma gene (pRB). We find that E2F-1 proteins are heterogeneously phosphorylated in insect cells, as a result of which they migrate as a doublet on SDS-polyacrylamide gels. This electrophoretic shift is shown to be dependent upon specific phosphorylation of E2F-1 on serine-375 (S375), near the pRB-binding site. Phosphorylation on S375 also occurs in human cells. E2F-1 was most efficiently phosphorylated on this residue by cyclin A/cdk2 kinase, and to a lesser extent by cyclin A/cdk2, irrespective of the presence of the pRB-related p107 protein. Phosphorylation of E2F-1 on S375 greatly enhanced its affinity of pRB in vitro. These results suggest a novel way of regulating E2F-1 activity, namely by cell-cycle-dependent phosphorylation of this transcription factor.

M3 - Journal article

C2 - 7824278

SN - 0950-9232

VL - 10

SP - 39

EP - 48

JO - Oncogene

JF - Oncogene

IS - 1

ER -