BIOLOGICAL SPECIFICITY AND MEASURABLE PHYSICAL-PROPERTIES OF CELL-SURFACE RECEPTORS AND THEIR POSSIBLE ROLE IN SIGNAL-TRANSDUCTION THROUGH THE CYTOSKELETON

It is proposed that the binding specificities of cell adhesion molecul es are manifested in their measurable physical properties. A method sp ecifically designed to measure the interfacial tension of cell aggrega tes is described. With the introduction of a statistical mechanical mo del, the measured values of tensions for aggregates consisting of gene tically engineered cells with controlled adhesive properties are used to obtain information on the strength of individual receptor-ligand bo nds. The strength of binding must depend on the receptor and its ligan d and reflects the amino acid sequence of the binding proteins. Many o f the cell surface receptors, being transmembrane proteins, are attach ed to the various macromolecular networks of the cytoskeleton; therefo re, it is suggested that their ligation and ensuing conformational cha nge may substantially affect the mechanical state of the cytoskeletal assemblies. Since these assemblies are believed to actively participat e in intracellular signaling by transmitting signals from the cell mem brane into the nucleus, the cell adhesion molecules may influence sign aling in a predictable way through their measurable physical character istics. In particular, varying bond strength at the cell surface may l ead to differential gene regulation.