Degradation of inositol 1,3,4,5-tetrakisphosphates by porcine brain cytosol yields inositol 1,3,4-trisphosphate and inositol 1,4,5-trisphosphate.
Inositol 1,3,4,5-tetrakisphosphates (Ins(1,3,4,5)P4), 32P-labelled in positions 4 and 5 were prepared enzymatically, using [4-32P]-phosphatidylinositol 4-phosphate (PtdInsP) and [5-32P]phosphatidylinositol 4,5-bisphosphate (PtdInsP2) as substrates, respectively. Degradation studies of Ins(1,3,4,5)P4, using an enriched phosphatase preparation from porcine brain cytosol, led to the formation of two inositol trisphosphate isomers which were identified as inositol 1,3,4-trisphosphate (Ins(1,3,4)P3) and inositol 1,4,5-trisphosphate (Ins(1,4,5)P3). This novel degradation pathway of Ins(1,3,4,5)P4 to Ins(1,4,5)P3 provides an additional source for the generation of Ins(1,4,5)P3, involving a 3-phosphatase.
Höer
D
D
Institut für Pharmakologie, Freie Universität Berlin, F.R.G.
Kwiatkowski
A
A
Seib
C
C
Rosenthal
W
W
Schultz
G
G
Oberdisse
E
E
D000818:Animals; D001921:Brain / Q000166:cytology* / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D015544:Inositol 1,4,5-Trisphosphate; D007295:Inositol Phosphates / Q000378:metabolism*; D007536:Isomerism; D009994:Osmolar Concentration; D013403:Sugar Phosphates / Q000378:metabolism*; D013552:Swine; D013997:Time Factors
D007295:Inositol Phosphates; D013403:Sugar Phosphates; C081655:inositol-1,3,4,5-tetrakisphosphate; D015544:Inositol 1,4,5-Trisphosphate