Thermotropic change in phospholipid packing in microsomal membranes sensed by phospholipase A2.

A reversible, temperature-dependent change in phospholipid packing occurring between 0 degree C and 12 degrees C has been identified in microsomal membranes by the use of phospholipase A2 from Crotalus atrox. It manifests itself as a drastic increase in susceptibility to the phospholipase and depends on non-lipid (presumably protein) membrane components. It is suggested that this change could underlie the change in transmembrane mobility of phospholipids which occurs in the same temperature range.