Are phospholipid-binding proteins in vivo phospholipase inhibitors?

Apo C1, a 6.5 kD protein component of VLDL, inhibits the hydrolysis of DPPC vesicles by pancreatic PLA2 and the hydrolysis of cellular phospholipids by endogenous phospholipases by interaction with the substrate. It is suggested that apo C1 and similar phospholipid-binding proteins modulate in vivo phospholipase activity, because they do so in cell homogenates with concentrations approximately equal to those found in the plasma.