<p>Cytochrome b561 is an integral membrane and electron transport protein, that binds two haem groups non-covalently. This domain is also found in a number of nickel-dependent hydrogenase subunits which are also B-type cytochromes that interact with quinones and anchor the hydrogenase to the membrane. Members of the 'eukaryotic cytochrome b561' family can be found in <db_xref db="INTERPRO" dbkey="IPR004877"/>.</p> Cytochrome b561, bacterial/Ni-hydrogenase