Component of the EKC/KEOPS complex that is required for the formation of a threonylcarbamoyl group on adenosine at position 37 (t(6)A37) in tRNAs that read codons beginning with adenine. The complex is probably involved in the transfer of the threonylcarbamoyl moiety of threonylcarbamoyl-AMP (TC-AMP) to the N6 group of A37. OSGEP likely plays a direct catalytic role in this reaction, but requires other protein(s) of the complex to fulfill this activity. adenosine(37) in tRNA + L-threonylcarbamoyladenylate = AMP + H(+) + N(6)-L-threonylcarbamoyladenosine(37) in tRNA Binds 1 divalent metal cation per subunit. Component of the EKC/KEOPS complex composed of at least GON7, TP53RK, TPRKB, OSGEP and LAGE3; the whole complex dimerizes. Widely expressed at low level. Expressed at intermediate level in lung. Weakly expressed in testis, skeletal muscle, kidney, liver, spleen, brain and heart. Weakly expressed in 7, 11 and 17 day embryos. Expressed at a higher level in 15 day embryos. Mouse embryos display primary microcephaly characterized by significantly shorter cortex lengths, cortex-midbrain midline lengths and cortex widths. Mice do not show a renal phenotype. Belongs to the KAE1 / TsaD family.