myo-Inositol monophosphatase in the brain has zinc ion-dependent tyrosine phosphatase activity.
1. myo-Inositol monophosphatase (E.C. 3.1.3.25) hydrolyzes inositol monophosphate to form free myo-inositol, the precursor for the inositol phospholipid second-messenger signaling systems. The biochemical properties of the enzyme were examined in detail. 2. The enzyme exhibited significant hydrolytic activity only on phosphotyrosine among physiological substrates tested in the presence of Zn2+ ions in an acidic environment. 3. The enzyme was recognized and immunoprecipitated with polyclonal antibodies developed against the Zn2+-dependent tyrosine phosphatase of bovine brain. 4. These results indicate that myo-inositol monophosphatase exhibits Zn2+-dependent tyrosine phosphatase activity in an acidic environment and has immunological identity with a Zn2+-dependent tyrosine phosphatase.
Department of Environmental Biochemistry, Kyoto Pharmaceutical University, Japan.
S
S
Fujimoto
J
J
Tsuda
N
N
Kawakami
H
H
Tanino
S
S
Shimohama
D000135:Acid Phosphatase / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000201:enzymology*; D002417:Cattle; D002845:Chromatography / Q000379:methods; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007294:Inositol / Q000378:metabolism; D008094:Lithium / Q000378:metabolism; D008670:Metals / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000302:isolation & purification / Q000378:metabolism*; D011233:Precipitin Tests; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D015290:Second Messenger Systems; D013379:Substrate Specificity; D014638:Vanadates / Q000494:pharmacology; D015032:Zinc / Q000378:metabolism*
D008670:Metals; D014638:Vanadates; D007294:Inositol; D008094:Lithium; D000135:Acid Phosphatase; D010744:Phosphoric Monoester Hydrolases; C021822:myo-inositol-1 (or 4)-monophosphatase; D017027:Protein Tyrosine Phosphatases; D015032:Zinc