Gly_His_Pro_Ser_Thr_tRNA synthetase class II core domain. This domain is the core catalytic domain of tRNA synthetases of the subgroup containing glycyl, histidyl, prolyl, seryl and threonyl tRNA synthetases. It is primarily responsible for ATP-dependent formation of the enzyme bound aminoacyl-adenylate. These enzymes belong to class II aminoacyl-tRNA synthetases (aaRS) based upon their structure and the presence of three characteristic sequence motifs in the core domain. This domain is also found at the C-terminus of eukaryotic GCN2 protein kinase and at the N-terminus of the ATP phosphoribosyltransferase accessory subunit, HisZ and the accessory subunit of mitochondrial polymerase gamma (Pol gamma b) . Most class II tRNA synthetases are dimers, with this subgroup consisting of mostly homodimers. These enzymes attach a specific amino acid to the 3' OH group of ribose of the appropriate tRNA.