<p>In <taxon tax_id="562">Escherichia coli</taxon> and many other bacteria, two small, hydrophobic, mutually homologous subunits of succinate dehydrogenase (a TCA cycle enzyme) are SdhC and SdhD. This entry is the SdhC, the cytochrome b subunit, called b556 in bacteria and b560 in mitochondria. SdhD (see <db_xref db="INTERPRO" dbkey="IPR014312"/>) is called the hydrophobic membrane anchor subunit, although both SdhC and SdhD participate in anchoring the complex. In some bacteria, this cytochrome b subunit is replaced my a member of the cytochrome b558 family (see <db_xref db="INTERPRO" dbkey="IPR011138"/>).</p> Succinate dehydrogenase, cytochrome b556 subunit