PROSITE documentation PDOC51079
MBT repeat profile


The Polycomb-group protein Sex Comb on midleg (SCM) and the tumor suppressor protein lethal (3) malignant brain tumor (l(3)mbt) , share a homology region consisting of two repeats, each about 100 amino acids in length. This repeat has been name MBT after its occurence in l(3)mbt [1].

The structure of MBT repeats has been solved (see <PDB:1OI1>) [2,3]. Each repeat consists of an extended "arm" and a globular core. The arm of the first repeat packs against the core of the second repeat and vice versa. The core consists of an SH3-like five stranded β-barrel followed by a C-terminal α-helice and another short β-strand. The MBT structure shows significant similarities with the Tudor (see <PDOC50304>), the PWWP (see <PDOC50812>) and the chromo (see <PDOC00517>) domains within the β-barrel portion of the structure. Given their similarity to these domains, a binding role is probable, and post-translationally modified histones are good candidates for binding targets [3,4].

The profile we developed covers the whole MBT repeat.

Last update:

February 2005 / First entry.


Technical section

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

MBT, PS51079; MBT repeat profile  (MATRIX)


1AuthorsBornemann D. Miller E. Simon J.
TitleThe Drosophila Polycomb group gene Sex comb on midleg (Scm) encodes a zinc finger protein with similarity to polyhomeotic protein.
SourceDevelopment 122:1621-1630(1996).
PubMed ID8625848

2AuthorsWang W.K. Tereshko V. Boccuni P. MacGrogan D. Nimer S.D. Patel D.J.
TitleMalignant brain tumor repeats: a three-leaved propeller architecture with ligand/peptide binding pockets.
SourceStructure 11:775-789(2003).
PubMed ID12842041

3AuthorsSathyamurthy A. Allen M.D. Murzin A.G. Bycroft M.
TitleCrystal structure of the malignant brain tumor (MBT) repeats in Sex Comb on Midleg-like 2 (SCML2).
SourceJ. Biol. Chem. 278:46968-46973(2003).
PubMed ID12952983

4AuthorsMaurer-Stroh S. Dickens N.J. Hughes-Davies L. Kouzarides T. Eisenhaber F. Ponting C.P.
SourceTrends Biochem. Sci. 28:69-74(2003).

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