Surface roughness and molecular orientation strongly influence the forward but not the reverse rates of cell-bound receptor-ligand binding

Just as the interactions of soluble proteins are affected by properties of the solvent, membrane protein interactions are influenced by the surface environment in which they reside. The present study is designed to address the following questions: What effect would a rough surface have on cell adhesion? How would the molecular orientation of the receptor affect binding? What are the mechanisms involved? Since expressing adhesion receptors on transfected cells with altered surface microtopology and coating proteins on surfaces with altered orientation are widely used, it is of general interest to obtain quantitative answers to these questions. These results are consistent with the hypothesis that increasing the smoothness of the cell surface and the uniformity of molecular orientation would increase the accessibility of the molecule's recognition site. But once the ligand "key" fits into the receptor "lock", the dissociation would be governed by the interaction local to the binding pocket but independent of other global factors such as orientation and surface roughness.