The YrhK-like protein family includes the B. subtilis YrhK protein Swiss:O05401 which is functionally uncharacterised. Its expression is under the control of the motility sigma factor sigma-D [1]. This domain family is found in bacteria, archaea and eukaryotes, and is approximately 60 amino acids in length.

1: Small genes under sporulation control in the Bacillus subtilis genome. Schmalisch M, Maiques E, Nikolov L, Camp AH, Chevreux B, Muffler A, Rodriguez S, Perkins J, Losick R; J Bacteriol. 2010;192:5402-5412. PMID:20709900