Alanine-tRNA ligase, mitochondrial; mitochondrial Alanyl-tRNA synthetase; AlaRS (AARS2, AARSL, KIAA1270)

Function

• catalyzes the attachment of alanine to tRNA(Ala) in a two-step reaction: alanine is first activated by ATP to form Ala-AMP & then transferred to the acceptor end of tRNA(Ala)
• also edits incorrectly charged tRNA(Ala) via its editing domain

Cofactor: binds 1 Zn+2 per subunit (putative)

ATP + L-alanine + tRNA(Ala)
          <-->
AMP + diphosphate + L-alanyl-tRNA(Ala)

Structure

• consists of three domains
  • N-terminal catalytic domain
  • editing domain
  • C-terminal C-Ala domain
• editing domain removes incorrectly charged amino acids
• C-Ala domain, along with tRNA(Ala), serves as a bridge to cooperatively bring together the editing & aminoacylation centers thus stimulating deacylation of misacylated tRNAs
• belongs to the class-II aminoacyl-tRNA synthetase family

Compartment

mitochondrial matrix

Pathology

• defects in AARS2 are the cause of combined oxidative phosphorylation deficiency type 8

More general terms

• amino acyl tRNA synthetase-2
• mitochondrial protein

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=57505
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:57505
• OMIM: https://mirror.omim.org/entry/612035
• OMIM: https://mirror.omim.org/entry/614096
• UniProt: http://www.uniprot.org/uniprot/Q5JTZ9.html