This family consists of several FlbT proteins. FlbT is a post-transcriptional regulator of flagellin. FlbT is associated with the 5' untranslated region (UTR) of fljK (25 kDa flagellin) mRNA and that this association requires a predicted loop structure in the transcript. Mutations within this loop abolish FlbT association and result in increased mRNA stability. It is therefore thought that FlbT promotes the degradation of flagellin mRNA by associating with the 5' UTR.