The lambda repressor contains two domains.

Publisher Website
Google Scholar
Abstract
Papain digestion of the .lambda. phage repressor produces 2 fragments that are relatively resistant to further digestion. One includes the amino [N] terminus (residues 1-92) and the other the C terminus (residues 132-236). Calorimetry shows that the N-terminal fragment denatures near 50.degree. C and that the C-terminal fragment denatures near 70.degree. C. Intact repressor undergoes 2 denaturations, one near 50.degree. C and another near 70.degree. C. These and other data show that .lambda. repressor consists of 2 domains joined by a connector 40 amino acids long that is sensitive to proteases. The N-terminal domain binds DNA, and the C-terminal domain oligomerizes.