SARP, a new alternatively spliced protein phosphatase 1 and DNA interacting protein.
PP1 (protein phosphatase 1) is a ubiquitously expressed serine/threonine-specific protein phosphatase whose activity towards different substrates appears to be mediated via binding to specific proteins that play critical regulatory and targeting roles. In the present paper we report the cloning and characterization of a new protein, termed SARP (several ankyrin repeat protein), which is shown to interact with all isoforms of PP1 by a variety of techniques. A region encompassing a consensus PP1-binding motif in SARP (K354VHF357) modulates endogenous SARP-PP1 activity in mammalian cells. This SARP-PP1 interaction motif lies partially within the first ankyrin repeat in contrast with other proteins [53BP2 (p53 binding protein 2), MYPT1/M(110)/MBS (myosin binding protein of PP1) and TIMAP (transforming growth factor beta inhibited, membrane-associated protein)], where a PP1-binding motif precedes the ankyrin repeats. Alternative mRNA splicing produces several isoforms of SARP from a single human gene at locus 11q14. SARP1 and/or SARP2 (92-95 kDa) are ubiquitously expressed in all tissues with high levels in testis and sperm, where they are shown to interact with both PP1gamma1 and PP1gamma2. SARP3 (65 kDa) is most abundant in brain where SARP isoforms interact with both PP1alpha and PP1gamma1. SARP is highly abundant in the nucleus of mammalian cells, consistent with the putative nuclear localization signal at the N-terminus. The presence of a leucine zipper near the C-terminus of SARP1 and SARP2, and the binding of mammalian DNA to SARP2, suggests that SARP1 and SARP2 may be transcription factors or DNA-associated proteins that modulate gene expression.
Browne
Gareth J
GJ
Medical Research Council Protein Phosphorylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK.
Fardilha
Margarida
M
Oxenham
Senga K
SK
Wu
Wenjuan
W
Helps
Nicholas R
NR
da Cruz E Silva
Odete A B
OA
Cohen
Patricia T W
PT
da Cruz E Silva
Edgar F
EF
D048868:Adaptor Proteins, Signal Transducing; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D017089:Ankyrin Repeat; D019556:COS Cells; D002467:Cell Nucleus / Q000378:metabolism; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005136:Eye Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016350:Leucine Zippers; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D054645:Protein Phosphatase 1; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D000094742:Secreted Frizzled-Related Proteins
D048868:Adaptor Proteins, Signal Transducing; D004247:DNA; D004268:DNA-Binding Proteins; D005136:Eye Proteins; D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D010749:Phosphoprotein Phosphatases; D020033:Protein Isoforms; D054645:Protein Phosphatase 1; D021122:Protein Subunits; C117636:SFRP1 protein, human; D000094742:Secreted Frizzled-Related Proteins; C109618:SFRP2 protein, human; C118511:SFRP5 protein, human