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Protein family review

KRAB-containing zinc-finger repressor proteins

Raul Urrutia

Author Affiliations

Gastroenterology Research Unit, Saint Mary's Hospital and Department of Biochemistry and Molecular Biology and Tumor Biology Program, Mayo Clinic, Rochester, MN 55905, USA

Genome Biology 2003, 4:231  doi:10.1186/gb-2003-4-10-231

Published: 23 September 2003

Abstract

The largest family of zinc-finger transcription factors comprises those containing the Kr├╝ppel-associated box (or KRAB domain), which are present only in tetrapod vertebrates. Many genes encoding KRAB-containing proteins are arranged in clusters in the human genome, with one cluster close to chromosome 9ql3 and others in centromeric and telomeric regions of other chromosomes, but other genes occur individually throughout the genome. The KRAB domain, which is found in the amino-terminal region of the proteins, behaves as a transcriptional repressor domain by binding to corepressor proteins, whereas the C2H2 zinc-finger motifs bind DNA. The functions currently proposed for members of the KRAB-containing protein family include transcriptional repression of RNA polymerase I, II, and III promoters and binding and splicing of RNA. Members of the family are involved in maintenance of the nucleolus, cell differentiation, cell proliferation, apoptosis, and neoplastic transformation.