Glutamyl-tRNA(Gln) amidotransferase subunit B, mitochondrial (Glu-AdT subunit B) is an enzyme that in humans is encoded by the GATB gene. This protein functions as the catalytic (enzyme) subunit of the protein complex Glu-tRNAGln amidotransferase (Glu-Adt) which is involved in protein synthesis in the mitochondria.
GATB together with GATA (QRSL1) and GATC form a complex called Glu-tRNAGln amidotransferase (Glu-Adt). This complex, and by extension Glu-AdT subunit B, functions to convert (mischarged) glutamyl-tRNAGln to glutaminyl-tRNAGln, which is used to incorporate glutamine into proteins during RNA-to-DNA translation.
Background and function
Proteins are synthesized with the help of special adaptor molecules called transfer RNA (tRNA), which connect messenger RNA (mRNA) sequences to their corresponding amino acid. Each tRNA has a corresponding amino acid it represents, and in the case of glutamine this type of RNA is denoted tRNAGln. In order to be used in mRNA-to-protein translation, the tRNA must be first charged with (attached to) the correct amino acid, producing a molecule called am aminoacyl-tRNA.
In most cases, including for glutamine in the human cytoplasm (see QARS1), aminoacyl-tRNA are produced by directly attaching the amino acid to its corresponding tRNA using enzymes called aminoacyl tRNA synthetases. However, this is not the case of glutamine in the mitochondria (and many bacteria). Instead the amino acid glutamate is first mischarged to tRNAGln (using EARS2), and then needs to be converted into glutamine by Glu-tRNAGln amidotransferase, which in humans is a protein complex formed out of QRSL1 (GATA), GATB, and GATC.
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