Alteration of myo-inositol monophosphatase in Alzheimer's disease brains.
myo-Inositol monophosphatase (E.C.3.1.3.25) catalyzes the hydrolysis of myo-inositol 1-phosphate in the presence of Mg2+ at a physiologic pH to form free myo-inositol, maintaining a supply that represents the precursor for inositol phospholipid second messenger signaling systems. In the present study the activity and protein level of myo-inositol monophosphatase were investigated in samples from normal human and Alzheimer's disease (AD) postmortem brains. The separation profile on Sephadex G-100 gel filtration chromatography revealed one major form of myo-inositol monophosphatase in crude extracts from both normal human and AD brains. In AD brains myo-inositol monophosphatase activity and its protein level were significantly higher than in control brains. The activity of myo-inositol monophosphatase per enzyme molecule was similar in control and AD brains. These results suggest that myo-inositol monophosphatase is upregulated in AD, probably reflecting compensatory mechanisms concerned with phospholipid metabolism.
Shimohama
S
S
Department of Neurology, Faculty of Medicine, Kyoto University, Japan. i53367@sakura.kudpc.kyoto-u.ac.jp
Tanino
H
H
Sumida
Y
Y
Tsuda
J
J
Fujimoto
S
S
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000201:enzymology*; D000818:Animals; D001921:Brain / Q000201:enzymology*; D006801:Humans; D010743:Phospholipids / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000032:analysis / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
D010743:Phospholipids; D010744:Phosphoric Monoester Hydrolases; C021822:myo-inositol-1 (or 4)-monophosphatase