THE APPLICATION OF THE PERCOLATION THEORY FOR THE DESCRIPTION OF THE PLASMA-MEMBRANE INTEGRAL PROTEIN MOBILITY AND THE HORMONE-STIMULATED ADENYLATE-CYCLASE ACTIVITY .1. THE INFLUENCE OF CHANGE IN THE FLUID LIPID FRACTION UPON THE MEMBRANE INTEGRAL PROTEIN MOBILITY AND HORMONE-STIMULATED ADENYLATE-CYCLASE ACTIVITY

The influence of ''fluid'' lipid fraction changes upon the mobility of membrane integral proteins and the hormone-stimulated adenylate cycla se activity was studied in rat reticulocyte plasma membrane. By using the technique of fluorescence recovery after photobleaching it was fou nd that decreasing of the ''fluid'' lipid fraction induced by the trea tment of plasma membrane with phospholipase A2 resulted in a decrease in the lateral diffusion coefficient and in the mobile fraction of int egral membrane proteins from 0,74.10(-10) cm2/s to 0,27.10(-10) cm2/c and 62,8 to 25,8% respectively. By using radioligand techniques the in trinsic activities of agonists: isoproterenol, adrenalin, noradrenalin ,- and their ability for stimulating the hormone - beta-adrenergic rec eptor - G(s)-protein complex formation decreased as the ''fluid'' lipi d fraction was reduced. It was shown that the hormone-stimulated adeny late cyclase activity and the plasma membrane integral protein mobilit y could be described in terms of the precolation theory.