Required for the formation of a threonylcarbamoyl group on adenosine at position 37 (t(6)A37) in tRNAs that read codons beginning with adenine. Is a component of the KEOPS complex that is probably involved in the transfer of the threonylcarbamoyl moiety of threonylcarbamoyl-AMP (TC-AMP) to the N6 group of A37. The Kae1 domain likely plays a direct catalytic role in this reaction. The Bud32 domain probably displays kinase activity that regulates Kae1 function. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] adenosine(37) in tRNA + L-threonylcarbamoyladenylate = AMP + H(+) + N(6)-L-threonylcarbamoyladenosine(37) in tRNA Binds 1 Fe(2+) ion per subunit. Component of the KEOPS complex that consists of Kae1, Bud32, Cgi121 and Pcc1; the whole complex dimerizes. In the N-terminal section; belongs to the KAE1 / TsaD family. In the C-terminal section; belongs to the protein kinase superfamily. Tyr protein kinase family. BUD32 subfamily. Truncated N-terminus.