Cloning and expression of a bovine adenosine A₁ receptor cDNA

A bovine brain adenosine A1 receptor cDNA encoding a 326 amino acid protein has been identified. This cDNA, which encodes a protein greater than 90% identical to analogous rat and dog receptors, was transiently expressed in COS-1 cells. Recombinant receptors exhibited the features of bovine A1 receptors that distinguish it from rat and canine receptors, including subnanomolar Ki for 1,3-dipropyl-8-cyclopentylxanthine, R-phenylisopropyl- adenosine (R-PIA) and xanthine amino conjugate, and the distinct potency order: R-PIA greater than S-PIA much greater than 5'-N-ethylcarboxamidoadenosine greater than 2'-chloroadenosine. The results indicate that the pharmacological differences between A1 adenosine receptors among species result from only minor differences in receptor structures.