Inhibition of translation by mRNA encoding NIPP-1, a nuclear inhibitor of protein phosphatase-1.
Transient transfection of COS-1 cells with an expression vector for NIPP-1, a nuclear subunit of protein phosphatase-1, did not result in an overexpression of NIPP-1 protein, although the levels of mRNA encoding NIPP-1 increased dramatically. Moreover, high concentrations of NIPP-1 mRNA inhibited the translation in reticulocyte lysates of various unrelated mRNAs. This inhibition of translation was caused by the NIPP-1 messenger and not by the translation product, since mutation of the start codon abolished NIPP-1 protein production, but had no influence on the translational inhibition. Analysis of deletion mutants showed that the inhibition was mediated by a 0.5-kb fragment in the 5'-end of the NIPP-1 mRNA. This region, when inserted in the 5'-untranslated region of the beta-galactosidase messenger, inhibited the translation of beta-galactosidase mRNA in COS-1 cells. A predicted highly stable secondary structure deltaG = -239.5 kJ/mol) is present between residues 300 and 500 of NIPP-1 mRNA. The possible importance of this structure in the translational inhibition is discussed.
Wera
S
S
Afdeling Biochemie, Faculteit Geneeskunde, Katholieke Universiteit Leuven, Belgium.
Van Eynde
A
A
Stalmans
W
W
Bollen
M
M
D000818:Animals; D019556:COS Cells; D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors*; D014176:Protein Biosynthesis; D011494:Protein Kinases / Q000502:physiology; D054645:Protein Phosphatase 1; D011506:Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000502:physiology*; D012156:Reticulocytes / Q000378:metabolism
D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D011506:Proteins; D012333:RNA, Messenger; C021042:protein phosphatase inhibitor-1; D011494:Protein Kinases; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1