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Pathway for inositol 1,3,4-trisphosphate and 1,4-bisphosphate metabolism

Journal Article · · Proc. Natl. Acad. Sci. U.S.A.; (United States)
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We prepared (/sup 3/H)inositol-,3-(/sup 32/P)phosphate-and 4-(/sup 32/P)phosphate-labeled inositol phosphate substrates to investigate the metabolism of inositol 1,3,4-trisphosphate and inositol 1,4-bisphosphate. In crude extracts of calf brain, inositol 1,3,4-trisphosphate is first converted to inositol 3,4-bisphosphate, then the inositol 3,4-bisphosphate intermediate is further converted to inositol 3-phosphate. Similarly, inositol 1,4-bisphosphate is converted to inositol 4-phosphate, and no inositol 1-phosphate is formed. We partially purified an enzyme that we tentatively name inositol polyphosphate 1-phosphatase. This cytosolic enzyme converts inositol 1,3,4-trisphosphate to inositol 3,4-bisphosphate and also converts inositol 1,4-bisphosphate to inositol 4-phosphate. The enzyme does not utilize inositol 1,3,4,5-tetrakisphosphate, inositol 1,4,5-trisphosphate, or inositol 1-phosphate as substrates. Thus, we propose a new scheme for inositol phosphate metabolism. According to this pathway inositol 1,4,5-trisphosphate and inositol 1,4-bisphosphate are degraded to inositol 4-phosphate. Inositol 1-phosphate, which is the major inositol monophosphate formed in stimulated brain, is derived either from phospholipase C cleavage of phosphatidylinositol or from the degradation of inositol cyclic phosphates.

Research Organization:
Washington Univ. School of Medicine, St. Louis, MO
OSTI ID:
6523308
Journal Information:
Proc. Natl. Acad. Sci. U.S.A.; (United States), Journal Name: Proc. Natl. Acad. Sci. U.S.A.; (United States) Vol. 8; ISSN PNASA
Country of Publication:
United States
Language:
English

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Related Subjects

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL MODELS
BIOLOGICAL PATHWAYS
BODY
BRAIN
CATTLE
CENTRAL NERVOUS SYSTEM
DAYS LIVING RADIOISOTOPES
DOMESTIC ANIMALS
ENZYMES
ESTERASES
ESTERS
FRACTIONATION
HYDROLASES
ISOTOPE APPLICATIONS
ISOTOPES
LABELLED COMPOUNDS
LIGHT NUCLEI
LIPIDS
MAMMALS
METABOLISM
NERVOUS SYSTEM
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
ORGANS
PHOSPHATASES
PHOSPHOLIPIDS
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
RADIOISOTOPES
RATS
RODENTS
RUMINANTS
SEPARATION PROCESSES
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES