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.
Center for Molecular Medicine/Institute of Biotechnology, University of Texas Health Science Center, San Antonio 78245.
T
T
Durfee
K
K
Becherer
P L
PL
Chen
S H
SH
Yeh
Y
Y
Yang
A E
AE
Kilburn
W H
WH
Lee
S J
SJ
Elledge
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