HEXO: Proteins and Enzymes

HEXO is a 50-kD protein containing a SAP domain capable of recognizing AT-rich scaffold-attachment regions (SARs) in chromosomal DNA, and a exonuclease domain similar to those of DEDD exonuclease family members. HEXO is an RNA exonuclease that binds to the 3' end of histone mRNAs and probably degrades them, suggesting that it plays an essential role in histone mRNA decay after replication. It is also able to degrade the 3' overhangs of short interfering RNAs (siRNAs) in vitro, suggesting a possible role as a regulator of RNA interference (RNAi).