FIGURE 1.

Sequences of transmembrane segments of CCK1R and CCK2R. Shown are the alignments of primary sequences of transmembrane segments of subtypes of CCK receptors with those residues lining the small molecule binding pocket shaded. Those residues that are different in the two receptors were exchanged in the chimeric constructs. These are numbered in italics according to the nomenclature of Ballesteros and Weinstein (30) based on the most highly conserved residue in each segment as number 50.