GXGXG domain. This domain of unknown function is found at the C-terminus of the large subunit (gltB) of glutamate synthase (GltS), in subunit C of tungsten formylmethanofuran dehydrogenase (FwdC) and in subunit C of molybdenum formylmethanofuran dehydrogenase (FmdC). It is also found in a primarily archeal group of proteins predicted to encode part of the large subunit of GltS. It is characterized by a repeated GXXGXXXG motif. GltS is a complex iron-sulfur flavoprotein that catalyzes the synthesis of L-glutamate from L-glutamine and 2-oxoglutarate. It requires the transfer of ammonia and electrons among three distinct active centers that carry out L-Gln hydrolysis, conversion of 2-oxoglutarate into L-Glu, and electron uptake from a donor. These catalytic sites occur in other domains within the protein or or encoded by separate genes, and are not present in the domain in this CD. FwdC and FmdC are reversible ion pumps that catalyze the formylation and deformylation of methanofuran in hyperthermophiles and bacteria. They require the presence of either tungstun (FwdC) or molybdenum (FmdC). The specific function of this domain also remains unidentified in the formylmethanofuran dehydrogenases.

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                  ....*....|....*....|....*....|....*...
gi 1007515040   1 MEEDWEVLRRLVYEFCECFRFDAEGILEREFMKIIPVS 38
Cdd:cd00981   195 TEEDLEFIEKYIEEFCKEFGYDKAEILDEEFTKLKPKS 232

Archaeal-type gltB domain. This domain shares sequence similarity with a region of unknown function found in the large subunit of glutamate synthase, which is encoded by gltB and found in most bacteria and eukaryotes. It is predicted to be homologous to the C-terminal domain of glutamate synthase based upon sequence similarity coupled with genome organization data, showing that this domain is found in a gene cluster with other domains of Glts, which are annotated. This domain is found primarily in archaea, but is also present in a few bacteria, likely as a result of lateral gene transfer.

                          10        20        30
                  ....*....|....*....|....*....|....*...
gi 1007515040   1 MEEDWEVLRRLVYEFCECFRFDAEGILEREFMKIIPVS 38
Cdd:cd00981   195 TEEDLEFIEKYIEEFCKEFGYDKAEILDEEFTKLKPKS 232

Archaeal-type gltB domain. This domain shares sequence similarity with a region of unknown function found in the large subunit of glutamate synthase, which is encoded by gltB and found in most bacteria and eukaryotes. It is predicted to be homologous to the C-terminal domain of glutamate synthase based upon sequence similarity coupled with genome organization data, showing that this domain is found in a gene cluster with other domains of Glts, which are annotated. This domain is found primarily in archaea, but is also present in a few bacteria, likely as a result of lateral gene transfer.

                          10        20        30
                  ....*....|....*....|....*....|....*...
gi 1007515040   1 MEEDWEVLRRLVYEFCECFRFDAEGILEREFMKIIPVS 38
Cdd:cd00981   195 TEEDLEFIEKYIEEFCKEFGYDKAEILDEEFTKLKPKS 232