The ABCs of the H2Bs: The histone H2B sequences, variants, and modifications.

Histone proteins are the building blocks of chromatin, and function by wrapping DNA into complex structures that control gene expression. Histone proteins are regulated by post-translational modifications (PTMs) and by histone variant exchange. In this review, we will provide an overview of one of these histones: H2B. We will first define the sequences of human and mouse H2B proteins and discuss potential designations for canonical H2B. We will also describe the differential functions of H2B variants compared with canonical H2B. Finally, we will summarize known H2B modifications and their functions in regulating transcription. Through review of H2B genes, proteins, variants, and modifications, we aim to highlight the importance of H2B for epigenetic and transcriptional regulation of the cell.