MBT

Present in Drosophila Scm, l(3)mbt, and vertebrate SCML2

• SMART accession number: SM00561
• Description: Present in Drosophila Scm, l(3)mbt, and vertebrate SCML2. These proteins are involved in transcriptional regulation.
• Interpro abstract (IPR004092):

  The function of the malignant brain tumor (MBT) repeat is unknown, but is found in a number of nuclear proteins involved in transcriptional repression. The repeat contains a completely conserved glutamate at its amino terminus that may be important for function.

  The crystal structure of the two MBT repeats of human SCM-like 2 protein has been reported. 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 structure of the core-interacting part of each arm consists of an N-terminal alpha-helix and a turn of 3 ₁₀ helix connected by a short beta-strand. The core consists of an Src homology 3-like five-stranded beta-barrel followed by a C-terminal alpha-helix and another short beta-strand. Each arm interacts with its partner core in a similar way, with the orientation of the N-terminal helix relative to the barrel varying slightly. There are also extensive interactions between the two barrels [ (PUBMED:12952983) ].

• GO process: regulation of transcription, DNA-templated (GO:0006355)
• GO component: nucleus (GO:0005634)

There are 15038 MBT domains in 5088 proteins in SMART's nrdb database.

Literature (relevant references for this domain)

Primary literature is listed below; Automatically-derived, secondary literature is also avaliable.

• Usui H, Ichikawa T, Kobayashi K, Kumanishi T
• Cloning of a novel murine gene Sfmbt, Scm-related gene containing four mbt domains, structurally belonging to the Polycomb group of genes.
• Gene. 2000; 248: 127-35

A novel cDNA clone encoding a protein structurally related to the transcriptional repressor Polycomb group (PcG) proteins, which regulate homeotic genes and others, was isolated from mouse and rat brain. The coding protein contained the SPM domain and mbt repeats, both of which are characteristic of the PcG proteins, and showed significant similarity in amino acid sequence to the Drosophila Sex comb on midleg (Scm) protein. Since this novel protein contains the mbt repeats in four tandem copies, we designated this murine gene as Sfmbt for Scm-related gene containing four mbt domains. Cloning and characterization of the mouse Sfmbt gene revealed that the coding sequence comprised 20 exons, dispersed along approximately 40kb, and mapped to the proximal part of Chromosome 14. Northern blot analysis showed that the Sfmbt mRNAs were expressed most abundantly in the adult testis, and less intensively in all other tissues examined.

• Wismar J et al.
• The Drosophila melanogaster tumor suppressor gene lethal(3)malignant brain tumor encodes a proline-rich protein with a novel zinc finger.
• Mech Dev. 1995; 53: 141-54

The lethal(3)malignant brain tumor [t(3)mbt] gene causes, when mutated, malignant growth of the adult optic neuroblasts and ganglion mother cells in the larval brain and imaginal disc overgrowth. Via overlapping deficiencies a genomic region of approximately 6.0 kb was identified, containing l(3)mbt+ gene sequences. The l(3)mbt+ gene encodes seven transcripts of 5.8 kb, 5.65 kb, 5.35 kb, 5.25 kb, 5.0 kb, 4.4 kb and 1.8 kb. The putative MBT163 protein, encompassing 1477 amino acids, is proline-rich and contains a novel zinc finger. In situ hybridizations of whole mount embryos and larval tissues revealed l(3)mbt+ RNA ubiquitously present in stage 1 embryos and throughout embryonic development in most tissues. In third instar larvae l(3)mbt+ RNA is detected in the adult optic anlagen and the imaginal discs, the tissues directly affected by l(3)mbt mutations, but also in tissues, showing normal development in the mutant, such as the gut, the goblet cells and the hematopoietic organs.

Structure (3D structures containing this domain)

3D Structures of MBT domains in PDB

PDB code	Title
1oi1	Crystal Structure of the MBT domains of Human SCML2
1oyx	CRYSTAL STRUCTURE OF 3-MBT REPEATS OF LETHAL (3) MALIGNANT BRAIN TUMOR (SELENO-MET) AT 1.85 ANGSTROM
1oz2	CRYSTAL STRUCTURE OF 3-MBT REPEATS OF LETHAL (3) MALIGNANT BRAIN TUMOR (NATIVE-II) AT 1.55 ANGSTROM
1oz3	Crystal Structure of 3-MBT repeats of lethal (3) malignant Brain Tumor (Native-I) at 1.85 angstrom
1wjq	Solution structure of the third mbt domain from human KIAA1798 protein
1wjr	Solution structure of the 2nd mbt domain from human KIAA1617 protein
1wjs	Solution structure of the first mbt domain from human KIAA1798 protein
2biv	Crystal structure of the wild-type MBT domains of Human SCML2
2eqm	Solution structure of the TUDOR domain of PHD finger protein 20-like 1 [Homo sapiens]
2jtf	Solution Structure of the PHF20L1 MBT domain
2p0k	Crystal structure of SCMH1
2pqw	Crystal structure of L3MBTL1 in complex with H4K20Me2 (residues 17-25), trigonal form
2r57	Crystal Structure of the two MBT repeats from Sex-Comb on Midleg (SCM)
2r58	Crystal Structure of the two MBT repeats from Sex-Comb on Midleg (SCM) in Complex with Di-Methyl Lysine
2r5a	Crystal Structure of the two MBT repeats from Sex-Comb on Midleg (SCM) in complex with methyl lysine
2r5m	Crystal Structure of the two MBT repeats from Sex-Comb on Midleg (SCM) in complex with peptide R-(me)K-S
2rhi	Crystal structure of the 3-MBT domain from human L3MBTL1 in complex with H1.5K27me2 at 1.66 angstrom
2rhu	Crystal structure of the 3-MBT repeats from human L3MBTL1 bound to dimethyl-lysine and in chimera with histone H3.3(28-34)
2rhx	Crystal structure of the 3-MBT repeats from human L3MBTL1 bound to dimethyl-lysine
2rhy	Crystal structure of the 3-MBT repeats from human L3MBTL1 bound to monomethyl-lysine
2rhz	Crystal structure of the 3-MBT repeats from human L3MBTL1 with D355N point mutation
2ri2	Crystal structure of the 3-MBT repeats from human L3MBTL1 with D355A point mutation
2ri3	Crystal structure of the 3-MBT repeats from human L3MBTL1 with N358Q point mutation
2ri5	Crystal structure of the 3-MBT repeats from human L3MBTL1 with N358A point mutation
2rjc	Crystal structure of L3MBTL1 protein in complex with MES
2rjd	Crystal structure of L3MBTL1 protein
2rje	Crystal structure of L3MBTL1 in complex with H4K20Me2 (residues 17-25), orthorhombic form II
2rjf	Crystal structure of L3MBTL1 in complex with H4K20Me2 (residues 12-30), orthorhombic form I
2vyt	The MBT repeats of human SCML2 bind to peptides containing mono methylated lysine.
3cey	Crystal structure of L3MBTL2
3f70	Crystal structure of L3MBTL2-H4K20me1 complex
3feo	The crystal structure of MBTD1
3h6z	Crystal Structure of the Four MBT Repeats of Drosophila melanogaster Sfmbt in Complex with Peptide RHR (me)K VLR
3oq5	Crystal structure of the 3-MBT domain from human L3MBTL1 in complex with p53K382me1
3p8h	Crystal structure of L3MBTL1 (MBT repeat) in complex with a nicotinamide antagonist
3ut1	Crystal structure of the 3-MBT repeat domain of L3MBTL3
3uwn	The 3-MBT repeat domain of L3MBTL1 in complex with a methyl-lysine mimic
4c5e	Crystal structure of the minimal Pho-Sfmbt complex (P21 spacegroup)
4c5g	Crystal structure of the minimal Pho-Sfmbt complex (P6122 spacegroup)
4c5h	Crystal structure of the minimal Pho-Sfmbt complex (P3121 spacegroup)
4c5i	Crystal structure of MBTD1 YY1 complex
4edu	The MBT repeats of human SCML2 in a complex with histone H2A peptide
4fl6	Crystal structure of the complex of the 3-MBT repeat domain of L3MBTL3 and UNC1215
4l59	Crystal structure of the 3-MBT repeat domain of L3MBTL3 and UNC2533 complex

Links (links to other resources describing this domain)

• INTERPRO: IPR004092