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Phosphorylation of I1PP2A at Tyrosine Residues in vivo
Protein phosphatase 2A (PP2A) is a divalent cation-independent protein serine/threonine phosphatase thought to be a key regulator in many different cell signaling pathways and an important determinant in tumorigenesis. The enzyme is inhibited potently by two naturally-occurring cancer- and apoptosis-associated cellular proteins termed I1PP2A and I2PP2A. Several forms of I1PP2A and I2PP2A are now known to exist in cells. I1PP2A(a), also termed PHAP-I, p32/33 and LANP, is highly expressed in some cancers.
Interestingly, recent studies by Yu L-G et al (J Biol Chem 279, 41377) showed that treatment of HT29 colon cancer cells with the antiproliferative lectin, jacalin, stimulates the phosphorylation of I1PP2A(a) at tyrosine residues. This phosphorylation results in the dissociation of PP2A from I1PP2A(a) and leads to the activation of the phosphatase. Activation of the phosphatase, a well known negative regulator of the ERK signaling pathway, in turn, caused the expected inactivation of MEK1/2 and ERK1/2. Because I1PP2A(a) binds to the catalytic C subunit of PP2A, which is present in all of the various PP2A complexes, it has been suggested that phosphorylation of I1PP2A(a) on tyrosine residues may represent a general mechanism for the regulation of PP2A activity and thus for control of the wide range of cellular functions that are regulated by the phosphatase. Whether the previously reported phosphorylations of I1PP2A(a) and I2PP2A(a) on serines regulates the interaction of these inhibitor proteins with PP2A remains to be determined.
Selected References
- Li M & Damuni Z (1998) Methods in Molecular Biology 93, 59
- Li M et al (1996) Biochemistry 35, 6998
- Vaesen M et al (1994) Biol Chem Hoppe Seyler 375, 113
- Yu L-G et al (2004) J Biol Chem 279, 41377
GloboZymes
6351 Corte del Abeto Suite 101
Carlsbad CA 92009, USA
Tel: 760-579-0393
Fax: 760-579-0394
email: info@globozymes.com
Web: www.GloboZymes.com
Spotlight on Protein Phosphatase 2A
Protein phosphatase 2A (PP2A) is a divalent cation-independent protein serine/threonine phosphatase involved in regulating numerous cellular processes including the cell cycle, growth and differentiation. Physiological targets of PP2A include cell surface receptors and ion channels, protein kinases involved in mitogenic signaling and the cell cycle, key regulatory enzymes and proteins involved in metabolism, as well as numerous transcription factors.
Protein phosphatase 2A has been implicated as a growth suppressor. It is inhibited potently by tumor promoters such as okadaic acid, and by I1PP2A and I2PP2A, two naturally-occurring cancer- and apoptosis-associated cellular proteins. Additionally, the SV40 small t antigen replaces the B subunit during viral transformation and subverts the physiological function of a subset of PP2A complexes in a substrate selective manner.
GloboZymes offers a diverse range of PP2A-related products, several of which are shown below.
Purified PP2A-Related Enzymes and Modulator Proteins
PP2A1 (1 μg)
PP2A1 (5 μg)
PP2A2 (1 μg)
PP2A2 (5 μg)
PP2AC
PP2A Subunit A (PR65)
PP2A Subunit AGlu416
I1PP2A(a)
I2PP2A(a)
I2PP2A(β)
I1PP2A(a) - GST tagged
I2PP2A(a) - GST tagged
PP2A-Related Antibodies and Detetction Kits
Anti-PP2AC (100 μl)
Anti-PP2AC (200 μl)
Anti-PP2AC Detection Kit.
Anti-I1PP2A (50 μl)
Anti-I1PP2A (100 μl)
Anti-I1PP2A Detection Kit
Anti-I2PP2A(a) (50 μl)
Anti-I2PP2A(a) (100 μl)
Anti-I2PP2A(a) Detection Kit
Selected References
- Amick GD et al (1992) Biochem J 287, 1019
- Guo H & Damuni Z (1993) Proc Natl Acad Sci USA 90, 2500
- Li M et al (1996) J Biol Chem 271, 11059
- Li M & Damuni Z (1998) Methods in Molecular Biology 93, 59
- Katayose Y et al (2000) J Biol Chem 275, 9209
- Al-Murrani SWK et al (1999) Biochem J. 341, 293
- Harmala-Brasken et al (2003) Oncogene 22, 7677
- Mayer-Jaekel RE & Hemmings BA (1994) Trends Cell Biol 4, 287
- Wera S & Hemmings BA (1994) Biochem J 311, 17
- Janssens V & Goris J (2001) Biochem J 353, 417
- Mumby MC & Walter G (1993) Physiol Rev 73, 673
- Walter G & Mumby MC (1993) Biochim Biophys Acta 1155, 207
GloboZymes
6351 Corte del Abeto Suite 101
Carlsbad CA 92011, USA
Tel: 760-579-0393
Fax: 760-579-0394
email: info@globozymes.com
Web: www.GloboZymes.com
GloboZymes 2004 Catalog Released
Carlsbad California, January 2004 - GloboZymes announces the availability of its 2004 product catalog featuring its top quality signal transduction products. This new, easy-to-use catalog includes product details, technical information, and key literature references. Product categories include Protein Kinases, Protein Phosphatases, Modulator Proteins, Protein Kinase Substrates, Protein Kinase Assay Kits, Protein Synthesis Initiation Factors, Antibodies, and Western Blot Detection Kits.
GloboZymes 2004 catalog is divided into sections based on product categories, and is fully cross-referenced with alternate product names. The Product Index serves as a complete guide to all products listed in the catalog.
GloboZymes president Dr. Zahi Damuni said: "We are very happy with our 2004 catalog. It provides useful information on each of our products in an easy-to-follow and well-illustrated format."
GloboZymes line of products are top quality, competitively priced and in stock for immediate shipment.
To receive GloboZymes 2004 catalog, just tell us where to send it, e-mail us at catalog@globozymes.com, call toll-free 866-891-0439, or write to GloboZymes, 6351 Corte del Aberto Suite 101, Carlsbad, CA 92011.
Press contact:
GloboZymes Media
6351 Corte del Abeto Suite 101
Carlsbad CA 92011, USA
Tel: 760-579-0393
Fax: 760-579-0394
email: info@globozymes.com
Web: www.GloboZymes.com
For earlier press releases, go to News Archives
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