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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 . It has been shown to be
essential but not sufficient to localize the PML protein in a punctate pattern
in interphase nuclei .
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 .
Proteins currently known to include the zinc finger B-box domain are listed
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
Human 52 Kd RO/SS-A protein. A protein of unknown function from the RO/SS-A
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
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 .
We developed a profile that covers the whole domain.
December 2001 / First entry.
PROSITE method (with tools and information) covered by this documentation:
RING fingers and B-boxes: zinc-binding protein-protein interaction domains.
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