Binds to regulatory subunit (RII) of protein kinase A. May be involved in establishing polarity in signaling systems or in integrating PKA-RII isoforms with downstream effectors to capture, amplify and focus diffuse, trans-cellular signals carried by cAMP. Highly expressed in lung and weakly in thymus and cerebellum. Little or no expression in liver, heart and cerebral cortex. All isoforms are expressed in lung, but KL2A and KL2B isoforms are the principal isoforms in cerebellum. The RII-alpha binding site, predicted to form an amphipathic helix, could participate in protein-protein interactions with a complementary surface on the R-subunit dimer. Produced by alternative splicing. Produced by alternative splicing. Produced by alternative initiation at Met-125 of isoform KL1A. Produced by alternative initiation at Met-125 of isoform KL2A.