Cleaved Histone H3 (Thr22) (D7J2K) Rabbit mAb #12576

Modulation of chromatin structure has a critical role in the control of various DNA directed activities such as transcription, DNA replication, and repair (1). The basic unit of chromatin, the nucleosome, consists of two turns of DNA wrapped around two copies each of four core histone proteins (H2A, H2B, H3, and H4) (2,3). Amino-terminal tails of histones undergo various post-translational modifications such as acetylation, methylation, phosphorylation, and ubiquitination in response to physiological and environmental stimuli. These modifications modulate the accessibility of chromatin to effector proteins as well as act as binding sites for specific histone modification recognizing effector proteins that regulate gene expression (1,4,5). Such alterations in chromatin modifications and architecture that accompany gene expression changes have been observed during embryonic stem cell differentiation (6). One of the ways in which chromatin modifications may be altered in stem cells involves regulated proteolysis of histone H3 by Cathepsin L. Cathepsin L cleaves the histone H3 amino-terminal tail predominantly at Thr22 in differentiating stem cells, leading to removal of histone modification marks which could then influence the expression patterns of developmentally regulated genes (7).