Anti-I1PP2A

Background: The PP2A inhibitor proteins, I1PP2A and I2PP2A, were discovered by GloboZymes founder Dr. Zahi Damuni during his tenure as professor at The Pennsylvania State University College of Medicine. Numerous laboratories around the world have since demonstrated further the significance of these proteins including in various diseases such as cancer and alzheimers. Purified preparations of I1PP2A inhibit all forms of protein phosphatase 2A (PP2A) tested to date in a substrate-selective manner. The purified preparations inhibit PP2A potently (k_i ~ 0.1 – 0.5 nM) with Myelin Basic Protein (MBP) and Histone H1 but not with Casein as substrate. In contrast, I1PP2A stimulates PP1 activity in the presence of Mn2+. In cells, I1PP2A undergoes phosphorylation on serine and tyrosine residues. The functional significance of the serine phosphorylations is unclear. Tyrosine phsophorylation of I1PP2A occurs in response to the antiproliferative lectin Jacalin. It causes the dissociation of the I1PP2A PP2A complex, with the concomitant activation of the phosphatase.

Figure: Western Blotting of purified preparations of I1PP2A with Anti-I1PP2A Polyclonal Antibody.

References:  Li M, Makkinje A, Damuni Z. (1996) Biochemistry 35, 6998-7002; Vaesen, M. et al (1994) Biol Chem Hoppe Seyler 375, 113-126; Malek, S. N. et al (1990) J Biol Chem 265, 13400-13409; Li, M., Damuni, Z. (1998) Methods Mol Biol  93, 59-66; Katayose, Y. et al (2000) J Biol Chem 275, 9209-9214; Yu L-G et al (2004) J Biol Chem 279, 41377-41383