NIPP-1, a nuclear inhibitory subunit of protein phosphatase-1, has RNA-binding properties.
NIPP-1 is a nuclear inhibitory subunit of protein phosphatase-1 with structural similarities to some proteins involved in RNA processing. We report here that baculovirus-expressed recombinant NIPP-1 displays RNA-binding properties, as revealed by North-Western analysis, by UV-mediated cross-linking, by RNA mobility-shift assays, and by chromatography on poly(U)-Sepharose. NIPP-1 preferentially bound to U-rich sequences, including RNA-destabilizing AUUUA motifs. NIPP-1 also associated with single-stranded DNA, but had no affinity for double-stranded DNA. The binding of NIPP-1 to RNA was blocked by antibodies directed against the COOH terminus of NIPP-1, but was not affected by prior phosphorylation of NIPP-1 with protein kinase A or casein kinase-2, which decreases the affinity of NIPP-1 for protein phosphatase-1. The catalytic subunit of protein phosphatase-1 did not bind to poly(U)-Sepharose, but it bound very tightly after complexation with NIPP-1. These data are in agreement with a function of NIPP-1 in targeting protein phosphatase-1 to RNA.
Jagiello
I
I
Afdeling Biochemie, Faculteit Geneeskunde, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium.
Beullens
M
M
Vulsteke
V
V
Wera
S
S
Sohlberg
B
B
Stalmans
W
W
von Gabain
A
A
Bollen
M
M
D000818:Animals; D001667:Binding, Competitive; D002352:Carrier Proteins; D002417:Cattle; D004722:Endoribonucleases / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D054645:Protein Phosphatase 1; D012313:RNA / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism*; D013950:Thymus Gland / Q000737:chemistry
D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D016601:RNA-Binding Proteins; C021042:protein phosphatase inhibitor-1; D012313:RNA; D004722:Endoribonucleases; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1