Many of the interactions studied in the biological and biomedical sciences occur with receptors at cell membrane surfaces. Prominent examples are neurotransmitters, cytokine receptors, tyrosine kinase receptors, ligang-and voltage-gated ion channels, G protein-coupled receptors, and antibody receptors. Interactions with these receptors are of special importance not only to academics, but also to the pharmaceutical industry as almost half of the 100 best-selling drugs on the market are targeted to a membrane receptor. More than 50% of current drug targets are membrane bound.Naturally, there...