Conformation and domain structure of the non‐histone chromosomal proteins HMG 1 and 2

Abstract
The sequence of the 224 residues of HMG 1 [high mobility group 1] suggests it consists of 3 domains. The A and B domains can fold autonomously and there is also a small N domain. Several proteases are now found to cut at the end of the B domain (at or close to residue 184). The A + B-domain fragment also folds and probably contains all the helix of intact HMG 1. The stability of the B domain is enhanced by the presence of the A domain. The acidic C domain undergoes a coil .fwdarw. helix transition on lowering the pH. Several peptides were prepared by clevage at Trp. Peptide 57-C-terminus contains complete B and C domains but does not fold. In the absence of the A domain the C domain is thus able to destabilize the B domain. The stability of the B domain in HMG 1 is due to interaction with the A domain and the C domain has a separate function from the other domains.