Association of phospholipase C-delta with a highly enriched preparation of canine sarcolemma
Wolf, R.A.
American Journal of Physiology 263(5 Pt 1): C1021-C1028
1992
ISSN/ISBN: 0002-9513 PMID: 1443097 Document Number: 396585
Myocardial synthesis of phosphatidylinositol 4,5-bisphosphate (PIP-2) is highly compartmentalized in the sarcolemmal membrane. Sarcolemmal vesicles contain endogenous phospholipase C (PLC), but the identity of sarcolemmal PLC and its relationship to soluble PLC have not been determined previously. Sarcolemmal and cytosolic PLC were prepared from canine myocardium and characterized by DEAE-cellulose chromatography and by immunoblotting with monoclonal and polyclonal antibodies to isoenzymes of PLC (PLC-beta, PLC-gamma, and PLC-delta). DEAE-cellulose chromatography resolved two forms of cytosolic PLC that were identified as an 85-kDa form of PLC-delta and a 145-kDa form of PLC-gamma. In contrast, DEAE-cellulose chromatography resolved a single form of sarcolemmal PLC that was identified as an 85-kDa form of PLC-delta. These data demonstrate that PLC-gamma and PLC-delta are are expressed in canine myocardium and that an 85-kDa form of PLC-delta is selectively associated with sites of PIP-2 synthesis in a highly enriched preparation of sarcolemma. These data do not exclude the existence of additional isoenzymes of sarcolemmal PLC that may have been removed during isolation of sarcolemmal membranes.