YRDC (yrdC N6-threonylcarbamoyltransferase domain containing) is a cytoplasmic and mitochondrial enzyme that catalyzes formation of N6-threonylcarbamoyladenosine (t6A) at position 37 of transfer RNAs (tRNAs) that decode codons beginning with adenine 1. The enzyme converts L-threonine, bicarbonate/CO2, and ATP to generate threonylcarbamoyl-AMP as an acyladenylate intermediate, releasing diphosphate 1. This modification is essential for proper translation fidelity and regulation of translational efficiency 2. YRDC operates within the conserved KEOPS complex in eukaryotes, cooperating with other subunits to achieve t6A biosynthesis 2. The enzyme is ubiquitously expressed across human tissues and highly evolutionarily conserved 3. Clinically, YRDC is dysregulated across multiple cancer types and associated with worse prognosis 4. In glioblastoma stem cells, YRDC is essential for elevated protein translation and tumor growth, with threonine accumulation facilitating t6A-mediated codon-biased translational reprogramming toward mitosis-related genes 5. YRDC promotes hepatocellular carcinoma progression via MEK/ERK signaling 6 and drives EGFR-TKI resistance in non-small cell lung cancer through regulated YRDC translation 7. Mutations in YRDC cause Galloway-Mowat syndrome 10, highlighting its critical cellular importance.