In rabbit proximal tubules, a basolateral ATP- and taurine-sensitive K⁺ channel (K_ATP) has been shown to be involved in membrane cross-talk, i.e. in the parallel changes observed between the rate of apical Na⁺ entry and the basolateral K⁺ conductance. As the molecular identity of this channel is still unsettled, we used degenerated primers designed from the sequences of different species to look for the presence of cDNA transcripts for inwardly rectifying K⁺ channel (Kir6.1&6.2) and for sulfonylurea receptors (SUR1, 2A & 2B) in a cDNA library obtained from rabbit proximal tubules suspension. PCR products for Kir6.1, SUR2A and SUR2B were identified while no product could be found for Kir6.2 or SUR1. Expression of the renal rabbit Kir6.1 in Xenopus oocytes generated a functional K⁺ channel; the induced K⁺ current was activated by lowering intracellular [ATP] (10 minutes incubation with 3mM NaAzide), responded to changes in external [K⁺] and was inhibited by 5mM external barium and 40 mM intracellular taurine. To study the specificity of the taurine sensitivity, the effect of this intracellular osmolyte was tested on several members of the inward rectifier familly (Kir) expressed in Xenopus oocytes. K⁺ currents induced by Kir1.1a, Kir2.1, Kir3.2, Kir4.1 or Kir5.1 were insensitive to taurine. All tested combinations of Kir6.x with or without SUR subunit were significantly inhibited by taurine, suggesting that taurine-sensitivity is a specific propertie of the Kir6 subgroup. Expression of Kir6.1 with SUR2A or SUR2B developed a K⁺ current sensitive to µM concentration of glibenclamide. In summary, our study suggests that the rabbit-PCT K_ATP channel is formed by a combination of Kir6.1 plus SUR2A and/or SUR2B.