Family member DsvC has been observed to co-purify with Desulfovibrio vulgaris dissimilatory sulfite reductase, and many members of this family are annotated as the third (gamma) subunit of dissimilatory sulphite reductase. However, this protein appears to be only loosely associated to the sulfite reductase, which suggests that DsrC may not be an integral part of the dissimilatory sulphite reductase. Members of this family are found in organisms such as E. coli and H. influenzae which do not contain dissimilatory sulphite reductases but can synthesize assimilatory sirohaem sulphite and nitrite reductases. It is speculated that DsrC may be involved in the assembly, folding or stabilisation of sirohaem proteins. The strictly conserved cysteine in the C-terminus suggests that DsrC may have a catalytic function in the metabolism of sulphur compounds.