Phosphorylation of the retinoblastoma-related protein p130 in growth-arrested cells.
The retinoblastoma family of proteins including pRB, p107 and p130 undergoes cell cycle dependent phosphorylation during the mid-G1 to S phase transition. This phosphorylation is dependent upon the activity of cyclin D/cdk4. In contrast to pRB and p107, p130 is phosphorylated during G0 and the early G1 phase of the cell cycle. We observed that p130 is specifically phosphorylated on serine and threonine residues in T98G cells arrested in G0 by serum deprivation or density arrest. Identification of the phospho-serine and phospho-threonine residues revealed that most were clustered within a short co-linear region unique to p130, defined as the Loop. Deletion of the Loop region resulted in a change in the phosphorylation status of p130 under growth arrest conditions. Notably, deletion of the Loop did not affect the ability of p130 to bind to E2F-4 or SV40 Large T antigen, to induce growth arrest in Saos-2 cells, and to become hyperphosphorylated during the proliferative phase of the cell cycle. p130 undergoes specific G0 phosphorylation in a manner that distinguishes it from pRB and p107.
Canhoto
A J
AJ
Department of Adult Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, MA 02115, USA.
Chestukhin
A
A
Litovchick
L
L
DeCaprio
J A
JA
D000595:Amino Acid Sequence; D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000378:metabolism; D002455:Cell Division / Q000502:physiology; D016895:Culture Media, Serum-Free; D004268:DNA-Binding Proteins / Q000378:metabolism; D050704:E2F4 Transcription Factor; D005909:Glioblastoma / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D011506:Proteins; D051381:Rats; D016192:Resting Phase, Cell Cycle / Q000502:physiology*; D050717:Retinoblastoma-Like Protein p130; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured
D000952:Antigens, Polyomavirus Transforming; D016895:Culture Media, Serum-Free; D004268:DNA-Binding Proteins; D050704:E2F4 Transcription Factor; D010750:Phosphoproteins; D011506:Proteins; C493838:Rbl2 protein, mouse; C493839:Rbl2 protein, rat; D050717:Retinoblastoma-Like Protein p130; D014157:Transcription Factors