CCA tRNA nucleotidyltransferase 1, mitochondrial (EC 2.7.7.72) (Mitochondrial tRNA nucleotidyl transferase, CCA-adding) (mt CCA-adding enzyme) (mt tRNA CCA-diphosphorylase) (mt tRNA CCA-pyrophosphorylase) (mt tRNA adenylyltransferase)
1_MLRCL 6_ YHWHR 11_ PVLNR 16_ RWSRL 21_ CLPKQ 26_ YLFTM 31_ KLQSP 36_ EFQSL 41_ FTEGL 46_ KSLTE 51_ LFVKE 56_ NHELR 61_ IAGGA 66_ VRDLL 71_ NGVKP 76_ QDIDF 81_ ATTAT 86_ PTQMK 91_ EMFQS 96_ AGIRM 101_ INNRG 106_ EKHGT 111_ ITARL 116_ HEENF 121_ EITTL 126_ RIDVT 131_ TDGRH 136_ AEVEF 141_ TTDWQ 146_ KDAER 151_ RDLTI 156_ NSMFL 161_ GFDGT 166_ LFDYF 171_ NGYED 176_ LKNKK 181_ VRFVG 186_ HAKQR 191_ IQEDY 196_ LRILR 201_ YFRFY 206_ GRIVD 211_ KPGDH 216_ DPETL 221_ EAIAE 226_ NAKGL 231_ AGISG 236_ ERIWV 241_ ELKKI 246_ LVGNH 251_ VNHLI 256_ HLIYD 261_ LDVAP 266_ YIGLP 271_ ANASL 276_ EEFDK 281_ VSKNV 286_ DGFSP 291_ KPVTL 296_ LASLF 301_ KVQDD 306_ VTKLD 311_ LRLKI 316_ AKEEK 321_ NLGLF 326_ IVKNR 331_ KDLIK 336_ ATDSS 341_ DPLKP 346_ YQDFI 351_ IDSRE 356_ PDATT 361_ RVCEL 366_ LKYQG 371_ EHCLL 376_ KEMQQ 381_ WSIPP 386_ FPVSG 391_ HDIRK 396_ VGISS 401_ GKEIG 406_ ALLQQ 411_ LREQW 416_ KKSGY 421_ QMEKD 426_ELLSY
1: Nucleotidyltransferase that catalyzes the addition and repair of the essential 3'-terminal CCA sequence in tRNAs, which is necessary for the attachment of amino acids to the 3' terminus of tRNA molecules, using CTP and ATP as substrates (PubMed:11504732, PubMed:25193871, PubMed:25640237, PubMed:25652405, PubMed:29454993, PubMed:30959222, PubMed:31011209, PubMed:34023389). tRNA 3'-terminal CCA addition is required both for tRNA processing and repair (PubMed:22076379, PubMed:25640237). Promotes tRNA repair and recycling downstream of the ribosome-associated quality control (RQC) pathway by mediating addition of the tRNA 3'-terminal CCA following cleavage by ANKZF1 and repair by ELAC1 (PubMed:31011209). Also involved in tRNA surveillance by mediating tandem CCA addition to generate a CCACCA at the 3' terminus of unstable tRNAs and tRNA-like transcripts (PubMed:22076379, PubMed:25640237). While stable tRNAs receive only 3'-terminal CCA, unstable tRNAs beginning with GG are marked with CCACCA and rapidly degraded (PubMed:22076379, PubMed:25640237). The structural flexibility of RNA controls the choice between CCA versus CCACCA addition: following the first CCA addition cycle, nucleotide-binding to the active site triggers a clockwise screw motion, producing torque on the RNA (PubMed:25640237). This ejects stable RNAs, whereas unstable RNAs are refolded while bound to the enzyme and subjected to a second CCA catalytic cycle (PubMed:25640237)
2: Adds 2 C residues (CC-) to the 3' terminus of tRNA molecules instead of a complete CCA end as isoform 1 does (in vitro)