Competence stimulating peptide-1 is a 17 amino acids pheromone that is secreted by Streptococcus pneumoniae. CSP pheromone is used in-vivo for intercellular communication. This peptide activates signal transduction pathway ComABCDE, which regulates natural genetic transformation. The pheromone is ribosomally synthesized as precursor peptide. The mature pheromone is strain specific. CSP pheromone is produced by S. pneumoniae strain Rx, which is closely related to strain R6.