acetyl coenzyme A synthetase (ADP forming), alpha domain
Although technically reversible, it is believed that this group of ADP-dependent acetyl-CoA synthetases (ACS) act in the direction of acetate and ATP production in the organisms in which it has been characterized. In most species this protein exists as a fused alpha-beta domain polypeptide. In Pyrococcus and related species, however the domains exist as separate polypeptides. This model represents the alpha (N-terminal) domain. In Pyrococcus and related species there appears to have been the development of a paralogous family such that four other proteins are close relatives. In reference, one of these (along with its beta-domain partner) was characterized as ACS-II showing specificity for phenylacetyl-CoA. This model has been constructed to exclude these non-ACS-I paralogs. This may result in new, authentic ACS-I sequences falling below the trusted cutoff.