sentences:  Some other residues that are thought to be involved in the binding of non-peptide antagonists to NK1 receptor are Ser169, Glu193, Lys194, Phe264, Phe267, Pro271 and Tyr272.Each structural class of non-peptide NK1 receptor antagonists appears to interact with a specific set of residues within the common binding pocket.There are at least three essential elements which are important for the interactivity of a ligand with the NK1 receptor.