[A model of cooperative rearrangements of biological membranes without changes in the affinity of receptor binding centers].

A mathematical model is proposed for cooperative rearrangements induced by specific ligand in certain biomembrane domains. They are considered as the N-valent receptors undergoing rearrangement when n less than or equal to N ligand-binding receptor sites are occupied. The model predicts distinct sigmoidal dependence for change of some structural parameter on ligand concentration when the receptor site-ligand affinity remains constant as binding rises (positive cooperativity is absent).