Bacteriophage lambda, CIII, regulatory protein (IPR013056)

Short name: Phage_lambda_CIII

Overlapping homologous superfamilies


Family relationships



Bacteriophage lambda regulatory protein CIII is a small protein that plays a role in stabilising the CII transcriptional activator, via a mechanism that is not yet fully understood [PMID: 1828895, PMID: 2957696]. Stabilised CII activates CI, the gene for the repressor protein that prevents transcription of proteins required for lytic development. The central portion of the protein is well conserved and is both necessary and sufficient for the activity of the protein [PMID: 1828895]. Comparative analysis of the CIII sequence in lambda, Bacteriophage HK022 and the lambdoid Enterobacteria phage P22 has led to the suggestion that this central region assumes an amphipathic alpha-helical structure [PMID: 1828895].

The characteristics of the protein distribution suggest prophage matches in addition to the phage matches.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PROSITE patterns