The retinoblastoma protein associates with the protein phosphatase type 1 catalytic subunit.
The retinoblastoma protein (p110RB) interacts with many cellular proteins in complexes potentially important for its growth-suppressing function. We have developed and used an improved version of the yeast two-hybrid system to isolate human cDNAs encoding proteins able to bind p110RB. One clone encodes a novel type 1 protein phosphatase catalytic subunit (PP-1 alpha 2), which differs from the originally defined PP-1 alpha by an amino-terminal 11-amino-acid insert. In vitro-binding assays demonstrated that PP-1 alpha isoforms preferentially bind the hypophosphorylated form of p110RB. Moreover, similar p110RB sequences are required for binding PP-1 alpha 2 and SV40 large T antigen. Cell cycle synchrony experiments revealed that this association occurs from mitosis to early G1. The implications of these findings on the regulation of both proteins are discussed.
Durfee
T
T
Center for Molecular Medicine/Institute of Biotechnology, University of Texas Health Science Center, San Antonio 78245.
Becherer
K
K
Chen
P L
PL
Yeh
S H
SH
Yang
Y
Y
Kilburn
A E
AE
Lee
W H
WH
Elledge
S J
SJ
D000952:Antigens, Polyomavirus Transforming / Q000378:metabolism; D001483:Base Sequence; D002455:Cell Division / Q000235:genetics* / Q000502:physiology; D003001:Cloning, Molecular / Q000379:methods*; D004271:DNA, Fungal / Q000032:analysis; D004268:DNA-Binding Proteins; D004926:Escherichia coli / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D015698:Genomic Library; D006801:Humans; D007527:Isoenzymes / Q000235:genetics; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism*; D016160:Retinoblastoma Protein / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D013379:Substrate Specificity; D014157:Transcription Factors
D000952:Antigens, Polyomavirus Transforming; D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C052130:GAL4 protein, S cerevisiae; D007527:Isoenzymes; D046911:Macromolecular Substances; D011993:Recombinant Fusion Proteins; D016160:Retinoblastoma Protein; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D010749:Phosphoprotein Phosphatases