The RB2/p130 gene product is a nuclear protein whose phosphorylation is cell cycle regulated.
The Rb2/p130 protein has been shown to have a high sequence homology with the retinoblastoma gene product (pRb), one of the most well-characterized tumor suppressor genes, and with pRB-related p107, especially in their conserved pocket domains, which display a primary role in the function of these proteins. In this study, we report on the biochemical and immunocytochemical characterization of the Rb2/p130 protein, using a polyclonal antibody developed against its "spacer" region included in the pocket domain of the whole protein. We show that pRb2/p130 is a phosphoprotein located at the nuclear level and that its phosphorylation pathway can be dramatically reduced by phosphatase treatment. Moreover pRb2/p130 with p107, is one of the major targets of the E1A viral oncoprotein-associated kinase activity, showing a phosphorylation pattern which is modulated during the cell cycle, reaching a peak of activation at the onset of S-phase.
Baldi
A
A
Department of Microbiology/Immunology, Jefferson Cancer Institute, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
De Luca
A
A
Claudio
P P
PP
Baldi
F
F
Giordano
G G
GG
Tommasino
M
M
Paggi
M G
MG
Giordano
A
A
D000911:Antibodies, Monoclonal; D002453:Cell Cycle / Q000502:physiology*; D006801:Humans; D007150:Immunohistochemistry; D007163:Immunosorbent Techniques; D009154:Mutation; D009687:Nuclear Proteins / Q000378:metabolism*; D012516:Osteosarcoma; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011506:Proteins; D016160:Retinoblastoma Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D050717:Retinoblastoma-Like Protein p130; D016196:S Phase; D017385:Sequence Homology; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D009687:Nuclear Proteins; D010750:Phosphoproteins; D011506:Proteins; C493837:RBL2 protein, human; D016160:Retinoblastoma Protein; D050717:Retinoblastoma-Like Protein p130