Drosophila Histone H2A.2 is Associated with the Interbands of Polytene Chromosomes

Drosophila chromatin contains two antigenically distinct H2A histones, H2A.1 and H2A.2. Indirect immunofluorescence analyses revealed that anti-H2A.1 binding was distributed throughout polytene chromosomes, whereas anti-H2A.2 binding was interband-specific. Thus, H2A.2 probably contributes to the less compacted structure of interbands. Since each band-interband region is thought to contain a single gene, our results suggest that the distribution of H2A.2 echoes the functional organization of the Drosophila genome. Similar H2A histones occur in eukaryotes ranging from protozoa to mammals. Their placement might be an important determinant of chromatin structure.