Nucleosome distribution on the Jk and Ck immunoglobulin gene segments of mouse liver chromatin.

The chromatin structure of the transcriptionally inactive kappa immunoglobulin gene in mouse liver was investigated by mainly employing indirect endlabeling on Bsp RI restriction nuclease digestions of intact nuclei. The disclosed strong (about 85%) but not uniform protection of the Bsp RI sites by nucleosomes is inconsistent with both a uniquely sequence-oriented localization and a completely random distribution of nucleosomes in this region of the genome. Several possibly applicable models are discussed. A model with multiple phases and non-uniform linker lengths cannot be excluded; however a largely random localization with a weak superimposed organization in two confined areas was tested and found sufficient for explaining the data.