Send to

Choose Destination
Biochemistry. 1996 Jun 4;35(22):6998-7002.

Molecular identification of I1PP2A, a novel potent heat-stable inhibitor protein of protein phosphatase 2A.

Author information

Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, 17033, USA.


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.

[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for American Chemical Society
Loading ...
Support Center