INDUCTION OF ASYMMETRY INTO HOMODIMERS

The self-regulation of biological signalling receptors via homodimeriz ation is discussed in relation to the symmetry changes occurring when these receptors bind their target ligand. The idea of positive and neg ative cooperativity between dimerization and ligand binding, mediated by changes in the symmetry of the system, as a source of signalling co ntrol is considered; and an analogy made with the homodimerization of a glycopeptide antibiotic, ristocetin A, which displays negative coope rativity. Finally, the regulation of the bacterial aspartate receptor and the human growth hormone receptor is discussed as a function of li gand-induced asymmetry. (C) 1998 Wiley-Liss. Inc.