Cytoplasmic Kae1 (Kinase-Associated Endopeptidase 1) is the ortholog of bacterial TsaD (YgjD) and the paralog of mitochondrial Qri7. It is an iron metalloprotein. Together with other proteins of the so-called EKC/KEOPS complex (Bud32, Pcc1 and Cgi121), ATP, threonine and bicarbonate as cofactors, they catalyze the in vivo formation of t6A (threonyl-carbamoylation, probably a processive type of reaction) at position 37 of all eukaryotic tRNA decoding ANN codons (ile, Met, Thr, Lys, Asn, Arg and Ser). However the detailed stepwise mechanism of t6A formation is still not known (March 2012).
Gcn4 misregulation reveals a direct role for the evolutionary conserved EKC/KEOPS in the t6A modification of tRNAs.
Daugeron MC, Lenstra TL, Frizzarin M, El Yacoubi B, Liu X, Baudin-Baillieu A, Lijnzaad P, Decourty L, Saveanu C, Jacquier A, Holstege FC, de Crecy-Lagard V, van Tilbeurgh H, Libri D