Fig. 1

Schematic drawing of the interaction of histamine with the H2-histamine receptor
The amino acid sequences of the homologous regions of the H2-histamine and β2-adrenergic receptors (amino acids 186–190 and 203–207 on the respective receptors) are indicated below. The two alterations made in the mutant receptor are indicated with italics. (From Ref. 2.)