Journal of Lipid Research, Vol 25, 1528-1535, Copyright © 1984 by Lipid Research, Inc.
Phospholipids as dynamic participants in biological processes
DJ Hanahan and DR Nelson
Phospholipids are described as active biological molecules. Three
distinctly different roles are examined. The first centers on protein-
lipid interactions and the lipid requirement expressed by certain enzymes.
This category is illustrated by two soluble proteins of the blood
coagulation scheme, Factor IXa and Factor Xa, and by an integral membrane
protein, the (Ca2+ + Mg2+)-ATPase of human erythrocytes. The next two
examples depict phospholipids as active participants in membrane-mediated
events. In the first of these, termed the phosphoinositide effect, a
phospholipid becomes a substrate during membrane signaling, and its
products presumably act as second messengers. In the second example, a
phospholipid is a signal that, among other reactions, induces the
phosphoinositide effect. Here, the phospholipid (platelet activating
factor) serves as a lipid chemical mediator. These examples show that
phospholipids behave not only as structural molecules but also as dynamic,
functionally important components of cells.