tRNA methyltransferase 10 homolog C

TRMT10C (tRNA methyltransferase 10 homolog C) is a mitochondrial enzyme that catalyzes N(1)-methylation of tRNA and mRNA molecules, serving as a core component of the mitochondrial ribonuclease P complex (UniProt: Q7L0Y3). It functions as the catalytic subunit of the MRPP1-MRPP2 subcomplex, which processes precursor tRNAs by forming m1G9 and m1A9 methylation marks and facilitating downstream 3'-end processing. The protein also exhibits mRNA methyltransferase activity on mitochondrial transcripts such as MT-ND5.

TRMT10C operates within mitochondrial nucleoids where it coordinates RNA processing and ribosome assembly. Mutations in TRMT10C cause combined oxidative phosphorylation deficiency 30 (COXPD30), a severe autosomal recessive mitochondrial disorder characterized by lactic acidosis, hypotonia, and multi-system failure (UniProt: Q7L0Y3).

In Alzheimer's disease, TRMT10C is significantly down-regulated in post-mortem brain tissue compared to age-matched controls, with a mean log2 fold-change of −0.54 (Chaparral AD proteomics). This reduction may reflect compromised mitochondrial tRNA maturation and protein synthesis capacity in AD pathology, though the functional consequences require further investigation.