100 years lock-and-key concept: are peptide keys shaped and guided to their receptors by the target cell membrane?

The ideas developed in the Membrane Compartments Theory which allow a quantitative prediction of receptor preference are discussed in terms of our present knowledge of opioid and neurokinin receptor structure. Furthermore, conformations of regulatory peptides interacting with artificial lipid membranes are compared with those of chemically constrained molecules that react selectively with different receptor classes. Striking similarities in the topochemistry of molecules with similar activity were observed. The membrane-induced topomers were almost congruent with the artificial topomers that are selectively recognized by the same receptors.