| Abstract: | Four subtypes of adenosine receptors have been cloned in several laboratories. The receptors all interact with G proteins and span the plasma membrane 7 times. They range in size from 319 to 412 amino acids. Conservation of structure among 10 different receptor clones for various species suggests that ligand recognition sites involve amino acids in the 2, 3, and 7 transmembrane segments of receptors. Species differences in ligand binding to A1 receptors in tissues are very similar; for bovine receptors the affinity is R-PIA ? NECA, for canine receptors NECA ≥ R-PIA. Purified bovine A1 receptors functionally couple to the pertussis toxin sensitive recombinant G proteins, Gi1, Gi2, Gi3, and Go. © 1993 Wiley-Liss, Inc. |
