Phosphorylation of phosphatase inhibitor-2 (i-2) by a bovine thymus tyrosine protein kinase, p40

Conference · Fri May 01 04:00:00 EDT 1987 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:6416383

DePaoli-Roach, A A; Votaw, P; Zioncheck, T F; Harrison, M L; Geahlen, R L

Phosphatase inhibitor-2, a heat stable protein of Mr 22,800, is a regulatory component of the ATP-Mg-dependent phosphatase. It has been shown that in the cell tyrosine kinase activation can result in altered phosphorylation at serine and/or threonine residues, but the mechanism involved is unknown. The authors have found that i-2 is a substrate for a tyrosine specific protein kinase, p40, purified from bovine thymus. The purified enzyme is a monomer of Mr 40,000 that is autophosphorylated at tyrosine residue(s). The stoichiometry of phosphorylation of i-2 by this tyrosine protein kinase is up to 1 mol of phosphate per mol of i-2. Phosphoaminoacid analysis revealed that all the phosphate introduced was associated with tyrosine residues. Mapping of TSP-tryptic peptides by TLE and isoelectric focusing showed one major labeled fragment. Using the ATP-Mg-dependent phosphatase, a lesser extent of phosphorylation of i-2 by p40 was obtained although partial activation of the phosphatase was observed. The effect on the activity was not due to FA/GSK-3 contamination. These results could provide an important link between tyrosine protein kinase activity and modulation of phosphorylation at serine and/or threonine residues.

• Research Organization: Indiana Univ. School of Medicine, Indianapolis
• OSTI ID: 6416383
• Report Number(s): CONF-870644-
• Conference Information: Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 46:6
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CATTLE
CHEMICAL REACTIONS
DAYS LIVING RADIOISOTOPES
DOMESTIC ANIMALS
ENZYME ACTIVITY
ENZYME INHIBITORS
ENZYMES
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
MAMMALS
NUCLEI
ODD-ODD NUCLEI
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHORYLATION
PHOSPHOTRANSFERASES
RADIOISOTOPES
RUMINANTS
TRACER TECHNIQUES
TRANSFERASES
VERTEBRATES