AJP - Cell Physiology, Vol 263, Issue 5 C1021-C1028, Copyright © 1992 by American Physiological Society
Association of phospholipase C-delta with a highly enriched preparation of canine sarcolemma
R. A. Wolf
Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.
Myocardial synthesis of phosphatidylinositol 4,5-bisphosphate (PIP2) 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 expressed in canine myocardium and that an 85-kDa
form of PLC delta is selectively associated with sites of PIP2 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.
