Characterization of inositol monophosphatase in human cerebrospinal fluid.
Inositol monophosphatase (IMPase) has been identified and characterized in human lumbar cerebrospinal fluid (CSF). The CSF enzyme has a Km for inositol 1-phosphate (Ins(1)P; 0.12 mM), a magnesium dependence (optimum concentration 10 mM) and a sensitivity to inhibition by either the bisphosphonate inhibitor 1-(4-hydroxyphenyloxy)ethane-1,1-bisphosphonic acid (L-690,330) or LiCl (IC50's: 1.3 microM and 1.6 mM, respectively) similar to native human brain and human recombinant enzymes. In CSF, antiserum raised against purified bovine brain IMPase recognised a protein of 30 kDa, identical to that seen in human brain homogenate. It remains to be determined whether CSF IMPase activity may be a useful in vivo marker of CNS phosphatidyl inositol cycle activity in disorders where this signalling pathway may be altered (e.g. manic depression).
Atack
J R
JR
Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Harlow, UK.
Rapoport
S I
SI
Varley
C L
CL
D001921:Brain / Q000201:enzymology*; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D010744:Phosphoric Monoester Hydrolases / Q000134:cerebrospinal fluid* / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism
D011994:Recombinant Proteins; D010744:Phosphoric Monoester Hydrolases; C021822:myo-inositol-1 (or 4)-monophosphatase