Structures of major proteins involved in the mitochondrial transcription. CTD, C-terminal domain; HhH, helix-hairpin-helix motif; HMG1 and 2, high mobility group-like domain; MTS, matrix targeting sequence; NED, N-terminal extension domain; NTD, N-terminal domain; POLR, POLRMT binding domain of the TFB2M; PR, Promoter-interacting domain; PS, priming substrate-interacting domain; RNHF, RNaseH fold, RuvC type; SAM, S-adenosylmethionine-dependent methyltransferase-like domain; SL, specificity loop; TFB, TFB2M-binding domain.