Krueppel-associated box (KRAB)

Introduction

A domain of about 75 amino acids found in the N-terminal region of eukaryotic Krueppel-type C2H2 zinc finger proteins. It is enriched in charged amino acids.

Subregions A & B are predicted to fold into 2 amphipathic alpha-helices. The KRAB A & B boxes can be separated by variable spacer segments & many KRAB proteins contain only the A box.

The KRAB domain functions as a transcriptional repressor when tethered to the template DNA by a DNA-binding domain. A sequence of 45 amino acids in the KRAB A subdomain mediates transcriptional repression. The B box does not repress transcription by itself but does potentiate transcriptional repression by the KRAB A subdomain.

More general terms

• Zn+2-binding site
• domain