Inositol 1,3,4,5-tetrakisphosphate and inositol hexakisphosphate receptor proteins: isolation and characterization from rat brain.
High-affinity, membrane-associated inositol 1,3,4,5-tetrakisphosphate (IP4) and inositol hexakisphosphate (IP6) binding proteins were solubilized and isolated utilizing a heparin-agarose resin followed by an IP4 affinity resin. The IP6 receptor comprises a protein complex of 115-, 105-, and 50-kDa subunits, all of which comigrate under native conditions. The Kd of the receptor for IP6 is 12 nM, whereas inositol 1,3,4,5,6-pentakisphosphate (IP5), IP4, and inositol 1,4,5-trisphosphate (IP3) are 50%, 30%, and 15%, respectively, as potent. Two protein complexes copurify with the IP4 receptor fraction. A 182/123-kDa complex elutes first from the affinity column followed by a 174/84-kDa protein complex, which elutes at higher salt. Both complexes show high affinity for IP4 (Kd = 3-4 nM). IP5, IP6, and IP3 display approximately 25%, 10%, and 0.1%, respectively, the affinity of IP4. Ligand binding to IP6 and IP4 receptors is inhibited 50% by heparin at 0.1 microgram/ml. IP4 receptor proteins are stoichiometrically phosphorylated by cyclic AMP-dependent protein kinase and protein kinase C, whereas negligible phosphorylation is observed for the IP6 receptor.
Theibert
A B
AB
Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
Estevez
V A
VA
Ferris
C D
CD
Danoff
S K
SK
Barrow
R K
RK
Prestwich
G D
GD
Snyder
S H
SH
D000818:Animals; D002462:Cell Membrane / Q000737:chemistry; D002531:Cerebellum / Q000737:chemistry*; D002846:Chromatography, Affinity; D006863:Hydrogen-Ion Concentration; D007295:Inositol Phosphates / Q000378:metabolism*; D010766:Phosphorylation; D010833:Phytic Acid / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D051381:Rats; D011956:Receptors, Cell Surface / Q000302:isolation & purification* / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear
D007295:Inositol Phosphates; D011956:Receptors, Cell Surface; D018160:Receptors, Cytoplasmic and Nuclear; C068271:inositol hexakisphosphate receptor; C061107:inositol-1,3,4,5-tetrakisphosphate receptor; C081655:inositol-1,3,4,5-tetrakisphosphate; D010833:Phytic Acid; D011494:Protein Kinases; D011493:Protein Kinase C