IDENTIFICATION OF INTERACTING AMINO-ACIDS AT THE HISTONE 2A-2B BINDING-SITE

Histones 2A and 2B of calf thymus were cross-linked within intact nuclei by UV-irradiation. This procedure induces the formation of covalent cross-links between noncovalently interacting residues in the histones of native chromatin. Tryptic peptide and partial sequence analysis of the cross-linked product showed that the covalent linkage is between tyrosine-37, -40 or -42 of H2B and proline-26 of H2A. These residues constitute part of the hydrophobic H2A-H2B binding domain within the nucleosomes of native chromatin.