Heme-binding domain of the class III cytochrome C family and related proteins
This alignment models heme binding core motifs as encountered in the cytochrome C3 family and related proteins. Cytochrome C3 is a tetraheme protein found in sulfate-reducing bacteria which use either thiosulfate or sulfate as the ultimate electron acceptors. C3 is an integral part of a complex electron transfer chain. The model also contains triheme cytochromes C7 which function in electron transfer during Fe(III) respiration by Geobacter sulfurreducens (PpcA, PpcB, PpcC, PpcD, and PpcE) and four repeated core motifs as found in the 16-heme cytochrome C HmcA of Desulfovibrio vulgaris Hildenborough which plays a role in electron transfer through the membrane following periplasmic oxidation of hydrogen (resulting in sulfate reduction in the cytoplasm).