PROSITE documentation PDOC50119
Zinc finger B-box-type profile


The B-box zinc finger is an around 40 amino acids domain. One or two copies of this motif are generally associated with a RING finger and a coiled coil motif to form the so-called tripartite motif. It is found essentially in transcription factors, ribonucleoproteins and proto-oncoproteins, but no function is clearly assigned to this domain [1]. It has been shown to be essential but not sufficient to localize the PML protein in a punctate pattern in interphase nuclei [2].

Among the 7 possible ligands for the zinc atom contained in a B-box, only 4 are used and bind one zinc atom in a Cys2-His2 tetrahedral arrangement. The NMR analysis reveals that the B-box structure comprises two β-strands, two helical turns and three extended loop regions different from any other zinc binding motif [3].

Proteins currently known to include the zinc finger B-box domain are listed below:

  • Mammalian ARD1 protein. GTP-binding protein.
  • Mammalian PML, probable transcription factor. Involved in a form of acute promyelocytic leukemia (APL).
  • Mammalian TIF1, transcription intermediary factor 1. Interacts selectively in vitro with the AF2-activating domain of the estrogen receptors.
  • Mammalian RFP, ret finger Protein. May function in male germ cell development.
  • Human 52 Kd RO/SS-A protein. A protein of unknown function from the RO/SS-A ribonucleoprotein complex.
  • Human HT2A may play a significant role in mediating the biological activity of the HIV-1 tat protein in vivo. Binds specifically to the activation domain of HIV-1 tat and can also interact with the HIV-2 and EIAV tat proteins in vivo.
  • Mouse RPT1, trans-acting factor that regulates gene expression of interleukin 2 receptor α chain and of human immunodeficiency virus type 1.
  • PwA33, associated with the lambrush chromosome loops in Pleurodeles Waltlii, may function as a component of Ribonucleoprotein complexes.
  • Xenopus laevis XNF7 (Xenopus nuclear factor 7) protein. There are two isoformes (XNF7-O and XNF7-B) of this DNA binding protein. The B-box domain of XNF7-B was analysed by NMR [3].

We developed a profile that covers the whole domain.

Last update:

December 2001 / First entry.


Technical section

PROSITE method (with tools and information) covered by this documentation:

ZF_BBOX, PS50119; Zinc finger B-box type profile  (MATRIX)


1AuthorsBorden K.L.
TitleRING fingers and B-boxes: zinc-binding protein-protein interaction domains.
SourceBiochem. Cell Biol. 76:351-358(1998).
PubMed ID9923704

2AuthorsBorden K.L. Lally J.M. Martin S.R. O'Reilly N.J. Solomon E. Freemont P.S.
TitleIn vivo and in vitro characterization of the B1 and B2 zinc-binding domains from the acute promyelocytic leukemia protooncoprotein PML.
SourceProc. Natl. Acad. Sci. U.S.A. 93:1601-1606(1996).
PubMed ID8643677

3AuthorsBorden K.L. Lally J.M. Martin S.R. O'Reilly N.J. Etkin L.D. Freemont P.S.
TitleNovel topology of a zinc-binding domain from a protein involved in regulating early Xenopus development.
SourceEMBO J. 14:5947-5956(1995).
PubMed ID8846787

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