Molecular identification of I1PP2A, a novel potent heat-stable inhibitor protein of protein phosphatase 2A.
The amino acid sequences of two tryptic peptides derived from purified preparations of I1PP2A indicated that this potent heat-stable protein inhibitor of protein phosphatase 2A (PP2A) may be equivalent to putative histocompatibility leukocyte antigens class II-associated protein I (PHAP-I). Experiments using purified preparations of recombinant human PHAP-I confirmed that this protein inhibited PP2A. Half-maximal inhibition of the phosphatase occurred at about 4 nM PHAP-I, similar to the half-maximal inhibition obtained with purified preparations of bovine kidney I1PP2A. In addition, PHAP-I did not affect the activities of protein phosphatase 1, 2B, and 2C in a manner analogous to that of I1PP2A. Together, the results establish the identity of I1PP2A on a firm basis.
Li
M
M
Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, 17033, USA.
Makkinje
A
A
Damuni
Z
Z
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins; D002417:Cattle; D017931:DNA Primers / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D004722:Endoribonucleases; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology; D005786:Gene Expression Regulation; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D007544:Isopropyl Thiogalactoside / Q000494:pharmacology; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009687:Nuclear Proteins; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors*; D054645:Protein Phosphatase 1; D054648:Protein Phosphatase 2; D011506:Proteins / Q000737:chemistry* / Q000494:pharmacology; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000494:pharmacology; D017421:Sequence Analysis; D014357:Trypsin / Q000378:metabolism
C087425:ANP32A protein, human; D002352:Carrier Proteins; D017931:DNA Primers; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; D010455:Peptides; D011506:Proteins; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; C021042:protein phosphatase inhibitor-1; D007544:Isopropyl Thiogalactoside; D004722:Endoribonucleases; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D054648:Protein Phosphatase 2; C097081:PPP1R8 protein, human; D014357:Trypsin