A lysophosphoinositide-specific phospholipase C distinct from other phospholipase C families in rat brain.
Distinct phospholipase C activities capable of hydrolyzing lysophosphatidylinositol (lysoPI-PLC) or phosphatidylinositol (PI-PLC) have been demonstrated in rat brain membranes. Treatment of brain membranes with 1 M NaCl or 1% sodium cholate solubilized a majority of PI-PLC activity from the membranes, whereas a significant level of lysoPI-PLC activity still remained membrane-associated. Most of the lysoPI-PLC activity was recovered in a 0.5% sodium deoxycholate-0.25 M NaCl extract which contained only low levels of PI-PLC activity. Using the separated fractions, differences between lysoPI-PLC and the known PI-PLC isoforms were examined. A specific peptide inhibitor of PI-PLC, which was previously shown to interact with active site regions common to known PI-PLC activity. Immunoblot analysis of both the lysoPI-PLC-rich and PI-PLC-rich fractions revealed that an antiserum against PI-PLC delta 1 cross-reacted with other PI-PLC isoforms, but not significantly with lysoPI-PLC. Furthermore, lysoPI-PLC was more resistant to sulfhydryl reagents than was PI-PLC. Our results indicate that lysoPI-PLC is an enzyme distinct from PI-PLC and that lysoPI-PLC possesses a different active site than known PI-PLC isoforms.
Tsutsumi
T
T
Department of Biological Chemistry, Faculty of Pharmaceutical Sciences, Nagoya City University, Japan.
Kobayashi
T
T
Miyashita
M
M
Watanabe
S
S
Homma
Y
Y
Okuyama
H
H
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D001921:Brain / Q000201:enzymology*; D002462:Cell Membrane / Q000201:enzymology; D019826:Cholic Acid; D002793:Cholic Acids / Q000494:pharmacology; D006868:Hydrolysis; D015151:Immunoblotting; D008246:Lysophospholipids / Q000378:metabolism*; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology; D010716:Phosphatidylinositols / Q000378:metabolism*; D051381:Rats; D012965:Sodium Chloride / Q000494:pharmacology; D012995:Solubility; D013379:Substrate Specificity; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*
D002793:Cholic Acids; D008246:Lysophospholipids; D010455:Peptides; D010716:Phosphatidylinositols; C025449:lysophosphatidylinositol; D012965:Sodium Chloride; D010738:Type C Phospholipases; D019826:Cholic Acid