Biomaterial Database

Purification and characterization of a polyphosphoinositide phosphatase from rat brain. 1994

H M Hope, and L J Pike

Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110.

A novel membrane-bound polyphosphoinositide phosphatase has been purified 7700-fold from rat brain. A combination of gel filtration chromatography and SDS-polyacrylamide gel electrophoresis indicated that the enzyme is a monomer with a molecular weight of 85,000-90,000. Biochemical analysis of the polyphosphoinositide phosphatase demonstrated that the enzyme utilizes phosphatidylinositol(4)phosphate (PtdIns(4)P), phosphatidylinositol(3)phosphate (PtdIns(3)P), and phosphatidylinositol (4,5)bisphosphate (PtdIns(4,5)P2) as substrates. In the case of PtdIns(4,5)P2, the substrate is doubly dephosphorylated to yield PtdIns. The apparent Km values for PtdIns(4)P and PtdIns(4,5)P2 are 45 and 5 microM, respectively. Inositol(1,4)bisphosphate and inositol(1,4,5)trisphosphate neither serve as direct substrates for the polyphosphoinositide phosphatase nor inhibit its activity even at concentrations as high as 100 microM. Thus, the substrate specificity of the polyphosphoinositide phosphatase is distinct from that of previously identified phosphatases that utilize both inositol phospholipids and soluble inositol phosphates as substrates. The ability of the polyphosphoinositide phosphatase to hydrolyze phosphate from the 3-, 4-, or 5-position of the inositol ring suggests that this enzyme may play a key role in maintaining homeostasis among all forms of polyphosphoinositides.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008274	Magnesium	A metallic element that has the atomic symbol Mg, atomic number 12, and atomic weight 24.31. It is important for the activity of many enzymes, especially those involved in OXIDATIVE PHOSPHORYLATION.
D010716	Phosphatidylinositols	Derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to the hexahydroxy alcohol, myo-inositol. Complete hydrolysis yields 1 mole of glycerol, phosphoric acid, myo-inositol, and 2 moles of fatty acids.	Inositide Phospholipid,Inositol Phosphoglyceride,Inositol Phosphoglycerides,Inositol Phospholipid,Phosphoinositide,Phosphoinositides,PtdIns,Inositide Phospholipids,Inositol Phospholipids,Phosphatidyl Inositol,Phosphatidylinositol,Inositol, Phosphatidyl,Phosphoglyceride, Inositol,Phosphoglycerides, Inositol,Phospholipid, Inositide,Phospholipid, Inositol,Phospholipids, Inositide,Phospholipids, Inositol
D010744	Phosphoric Monoester Hydrolases	A group of hydrolases which catalyze the hydrolysis of monophosphoric esters with the production of one mole of orthophosphate.	Phosphatase,Phosphatases,Phosphohydrolase,Phosphohydrolases,Phosphomonoesterase,Phosphomonoesterases,Phosphoric Monoester Hydrolase,Hydrolase, Phosphoric Monoester,Hydrolases, Phosphoric Monoester,Monoester Hydrolase, Phosphoric
D001921	Brain	The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.	Encephalon
D006358	Hot Temperature	Presence of warmth or heat or a temperature notably higher than an accustomed norm.	Heat,Hot Temperatures,Temperature, Hot,Temperatures, Hot
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D051381	Rats	The common name for the genus Rattus.	Rattus,Rats, Laboratory,Rats, Norway,Rattus norvegicus,Laboratory Rat,Laboratory Rats,Norway Rat,Norway Rats,Rat,Rat, Laboratory,Rat, Norway,norvegicus, Rattus
D066298	In Vitro Techniques	Methods to study reactions or processes taking place in an artificial environment outside the living organism.	In Vitro Test,In Vitro Testing,In Vitro Tests,In Vitro as Topic,In Vitro,In Vitro Technique,In Vitro Testings,Technique, In Vitro,Techniques, In Vitro,Test, In Vitro,Testing, In Vitro,Testings, In Vitro,Tests, In Vitro,Vitro Testing, In