We cloned cDNAs of and characterized two novel human protein kinases, TRPM7/ChaK1 and TRPM6/ChaK2, which contain an alpha-kinase domain fused to an ion-channel belonging to the TRP superfamily of ion-channels. TRPM7/ChaK1 cDNA encodes a protein of 1864 amino acids that is expressed in all human tissues studied. TRPM6/ChaK2 cDNA encodes a protein of 2022 amino acids, is expressed only in some tissues, and is particularly abundant in kidney. Purified recombinant kinase domains of TRPM7/ChaK1 and TRPM6/ChaK2 (ChaK1 and ChaK2) were able to undergo autophosphorylation and to phosphorylate myelin basic protein on serine and threonine residues. Both protein kinases are dramatically activated by Mn2+ ions. ChaK1 and ChaK2 are insensitive to staurosporine, but can be inhibited by rottlerin. Both protein kinases are specific for ATP, and cannot use GTP or ATP-g-S as a substrate. Structural analysis of ChaK1 suggests an explanation for the nucleotide specificity of channel-kinases. In conjunction with previously reported effects of ATP-g-S and GTP on the ion-channel activity of TRPM7/ChaK1, our results provide further support for the conjecture that the kinase activity of TRPM7/ChaK1 is not necessary for it’s ion-channel activity. The evolutionary origin of channel-kinases and their possible physiological role is discussed.