Structure-function unitization model of biological membranes.

Abstract

In 1966 Green and Perdue1,2 proposed the repeating unit model of membrane structure, the central concept of which is the postulate that membranes are built up of lipoprotein repeating units. Each such unit was assumed to be a set of proteins associated hydrophobically with phospholipid. At that time many molecular features of the membrane were unresolved. Until these molecular details were clarified further progress in developing the repeating unit model was hampered. During the past several years many of the basic molecular parameters have been satisfactorily defined both experimentally and theoretically. The predominantly lamellar or bilayer character of phospholipid in membranes has been established firmly.3–5 The characteristic features of intrinsic (integral) membrane proteins and the distinction between intrinsic and extrinsic (peripheral) membrane proteins have been sharply drawn.6–11 The manner in which intrinsic proteins can associate hydrophobically with bilayer phospholipid has been more realistically evaluated. 12 The models of Vanderkooi and Green12 and of Singer and Nicolson8 rationalize in a satisfactory fashion the above mentioned molecular parameters of membrane structure. The way was thus cleared for a re-examination of the supramolecular features of membrane structure and for a more rigorous development of the lipoprotein repeating unit concept of Green and Perdue.1,2