text: Characterization of the RRNPP family of quorum sensing regulators (which stands for proteins Rap, NprR, PrgX, PlcRd) were used in comparisons with ropB to postulate its structural functions. The Rap protein derived from Bacilli regulates sporulation, the NprR protein in Bacillus thuringiensis regulates necrotrophism, the PrgX protein regulates conjugation in Enterococcus faecalis, and PlcR protein regulates transcription of virulence factors in both Bacullis thuringiensis and Bacillus cereus. Similarities were observed in conserved asparagine residues on the TPR motifs of each of these proteins and in ropB.