The protein encoded by the C 1 regulator gene of lambda (λ) bacteriophage (q.v.). This DNA-binding protein represses the transcription of genes that facilitate the lytic state and therefore keeps the virus in the lysogenic condition. The promoter for C 1 is to the immediate right of the gene, and during translation the host transcriptase moves to the left. Movement of this enzyme can be blocked by the cro repressor (q.v.), which binds to an operator that overlaps the C 1 promoter. The lambda repressor forms a dimer, which binds to DNA via a helix-turn-helix motif (q.v.). See Chronology, 1966, Ptashne; 1987, Anderson, Ptashne, and Harrison; regulator gene.
Subjects: Genetics and Genomics — Chemistry.