Cytoplasmic and mitochondrial threonylcarbamoyl-AMP synthase required for the formation of a threonylcarbamoyl group on adenosine at position 37 (t(6)A37) in tRNAs that read codons beginning with adenine (PubMed:29760464, PubMed:31481669, PubMed:34545459). Catalyzes the conversion of L-threonine, HCO(3)(-)/CO(2) and ATP to give threonylcarbamoyl-AMP (TC-AMP) as the acyladenylate intermediate, with the release of diphosphate (PubMed:29760464). Participates in t(6)A37 formation in cytoplasmic and mitochondrial tRNAs (PubMed:29760464). May regulate the activity of some transporters (By similarity). ATP + hydrogencarbonate + L-threonine = diphosphate + H2O + L-threonylcarbamoyladenylate Interacts with RSC1A1. A large fraction localizes in the cytoplasm, whereas a smaller fraction is imported to mitochondria. Ubiquitously expressed. The mitochondrial targeting sequence (MTS) is weak and only mediates import of a small fraction of YRDC in mitochondria. The disease is caused by variants affecting the gene represented in this entry. Belongs to the SUA5 family.