9.B.393.  The DUF2231 (DUF2231) Family 

These proteins are of about 150 to 200 aas in size and have 4 TMSs.  Some homologues are annotated as Rieske 2Fe-2S proteins, and others are annotated as rubrerythrin or rubredoxin-type Fe(cys)4 proteins.  Consequently, they may be redox proteins.


TC#NameOrganismal TypeExample

DUF2231 protein of 178 aas and 4 TMSs. It is a rubredoxin_like; nonheme iron binding domain containing a [Fe(SCys)4] center. The family includes rubredoxins, a small electron transfer protein, and a slightly smaller modular rubredoxin domain present in rubrerythrin and nigerythrin.

DUF2231 protein of archaeon CG07 (groundwater metagenome)


Rubrerythrin of 185 aas and 4 TMSs.

Rubreythrin of Anaeroarcus burkinensis


Uncharacterized protein of 186 aas and 4 TMSs.

UP of Geothermobacter ehrlichii


Rubredoxin of 209 aas and 4 C-terminal TM

Rubredoxin of Desulfococcus oleovorans


TC#NameOrganismal TypeExample

Uncharacterized protein of 158 aas and 4 TMSs.

UP of Bacteroidetes bacterium GWA2 (subsurface metagenome)


DUF2231 domain-containing protein of 168 aas and 4 TM

DUF2231 protein of Micromonospora maritima


Uncharacterized protein of 459 aas and 4 N-terminal TMSs that belong to the 9.B.393 family, but a much longer region C-terminal of this short domain that shows sequence similarity with TC family 1.B.14. 

UP of Aquimarina agarivorans