SoxF and SoxL family, Rieske domain; The Rieske domain is a [2Fe-2S] cluster binding domain involved in electron transfer. SoxF is a subunit of the terminal oxidase supercomplex SoxM in the plasma membrane of Sulfolobus acidocaldarius that combines features of a cytochrome bc(1) complex and a cytochrome. The Rieske domain of SoxF has a 12 residue insertion which is not found in eukaryotic and bacterial Rieske proteins and is thought to influence the redox properties of the iron-sulfur cluster. SoxL is a Rieske protein which may be part of an archaeal bc-complex homologue whose physiological function is still unknown. SoxL has two features not seen in other Rieske proteins; (i) a significantly greater distance between the two cluster-binding sites and (ii) an unexpected Pro -> Asp substitution at one of the cluster binding sites. SoxF and SoxL are found in archaea and in bacteria.
Jiyao W et al.(2023). "The conserved domain database in 2023.",