FeS cluster insertion, C-terminal, conserved site <p>These proteins in this entry are small (106 to 135 amino-acid residues in bacteria, about 200 residues in fungi) that contain a number of conserved regions. They appear to be associated with the process of FeS-cluster assembly. The HesB proteins are associated with the nif gene cluster and the Rhizobium gene IscN has been shown to be required for nitrogen fixation [<cite idref="PUB00017348"/>]. Nitrogenase includes multiple FeS clusters and many genes for their assembly. The <taxon tax_id="562">Escherichia coli</taxon> SufA protein is associated with SufS, a NifS homologue and SufD which are involved in the FeS cluster assembly of the FhnF protein [<cite idref="PUB00010345"/>]. The Azotobacter protein IscA (homologues of which are also found in E. coli) is associated which IscS, another NifS homologue and IscU, a nifU homologue as well as other factors consistent with a role in FeS cluster chemistry [<cite idref="PUB00017349"/>]. A homologue from Geobacter contains a selenocysteine in place of an otherwise invariant cysteine, further suggesting a role in redox chemistry.</p><p>This entry represents a conserved site in the C-terminal extremity, it contains two conserved cysteines.</p>