The methylated DNA binding protein-2-H1 (MDBP-2-H1) consists of histone H1 subtypes which are truncated at the C-terminus.

The methylated DNA binding protein-2-H1 (MDBP-2-H1), present in rooster liver, is a member of the histone H1 family which inhibits transcription by binding selectively to methylated promoters. Here we have determined the primary structure of MDBP-2-H1. A comparison between histone H1 and MDBP-2-H1 was achieved by analyzing reversed phase HPLC-purified and V8-digested proteins by mass spectrometry and/or microsequencing. In rooster liver the most abundant histone H1 subtypes are H1 01 and H1 11L. Similarly, MDBP-2-H1 contains the same subtypes of histone H1. The histone H1 subtype H1 01 in MDBP-2-H1 has 150 amino acids, whereas the full-size histone H1 01 is 218 amino acids. The difference in mass between the two proteins is explained by C-terminal truncation of histone H1 01.