Cell density-dependent gene expression is a common phenomenon in bacteria and a diverse array of traits are known to be regulated in this way, including light emission, virulence, sporulation, antibiotic production, plasmid-driven conjugation and genetic transformation. Such "quorum-sensing" mechanisms are well characterized in Gram negative bacteria where N-acyl homoserine lactones act as the diffusible communication molecules.

Similarly, a variety of processes in Gram positive bacteria are known to be regulated in a cell density-dependent manner, such as competence induction in Bacillus subtilis and Streptococcus pneumoniae, the virulence response in Staphylococcus aureus and the production of anti-microbial peptides by lactic acid bacteria. In all these systems the signal molecule is a post-translationally-modified peptide, secreted by an ATP-binding-cassette (ATP) transporter, which functions as the input signal for a specific sensor component of a two-component signal-transduction system.

Both the gene encoding the precursor of the peptide and the genes encoding the proteins involved in the two-component regulatory system, and/or those involved in the secretion of the peptide pheromone, are transcriptionally linked, and the synthesis of the peptide pheromones appears to be an autoregulatory process.