1K1B

Crystal structure of the ankyrin repeat domain of Bcl-3: a unique member of the IkappaB protein family

Summary for 1K1B

• Entry DOI: 10.2210/pdb1k1b/pdb
• Related: 1K1A
• Descriptor: B-cell lymphoma 3-encoded protein (2 entities in total)
• Functional Keywords: bcl-3, nf-kappab transcription factors, ikappab proteins, transcription
• Biological source: Homo sapiens (human)
• Cellular location: Nucleus: P20749
• Total number of polymer chains: 1
• Total formula weight: 25829.45

Authors

Michel, F.,Soler-Lopez, M.,Petosa, C.,Cramer, P.,Siebenlist, U.,Mueller, C.W. (deposition date: 2001-09-24, release date: 2001-11-21, Last modification date: 2023-08-16)

Primary citation

Michel, F.,Soler-Lopez, M.,Petosa, C.,Cramer, P.,Siebenlist, U.,Muller, C.W.
Crystal structure of the ankyrin repeat domain of Bcl-3: a unique member of the IkappaB protein family.
EMBO J., 20:6180-6190, 2001

PubMed Abstract: IkappaB proteins associate with the transcription factor NF-kappaB via their ankyrin repeat domain. Bcl-3 is an unusual IkappaB protein because it is primarily nucleoplasmic and can lead to enhanced NF-kappaB-dependent transcription, unlike the prototypical IkappaB protein IkappaBalpha, which inhibits NF-kappaB activity by retaining it in the cytoplasm. Here we report the 1.9 A crystal structure of the ankyrin repeat domain of human Bcl-3 and compare it with that of IkappaBalpha bound to NF-kappaB. The two structures are highly similar over the central ankyrin repeats but differ in the N-terminal repeat and at the C-terminus, where Bcl-3 contains a seventh repeat in place of the acidic PEST region of IkappaBalpha. Differences between the two structures suggest why Bcl-3 differs from IkappaBalpha in selectivity towards various NF-kappaB species, why Bcl-3 but not IkappaBalpha can associate with its NF-kappaB partner bound to DNA, and why two molecules of Bcl-3 but only one of IkappaBalpha can bind to its NF-kappaB partner. Comparison of the two structures thus provides an insight into the functional diversity of IkappaB proteins.

PubMed: 11707390
DOI: 10.1093/emboj/20.22.6180

Experimental method

X-RAY DIFFRACTION (1.9 Å)