SELECTIVE DISTRIBUTION OF HISTONE H1 VARIANTS AND HIGH-MOBILITY GROUPPROTEINS IN CHROMOSOMES

Recent results on the differential distribution of sequence variants o f histone H1, of proteins of the HMG 1/2 family, and of HMGI in polyte ne chromosomes are reviewed. Several organisms are known to contain tw o different HMG 1/2 proteins. In Chironomus, one of them is restricted to decondensed puffs and may have a specific function. One of the H1 variants of Chironomus is found only in a minority of chromosome bands and differs from the other H1 proteins of the organism by genomic org anization and by an inserted structural motif that is also present in single H1 variants of other organisms.