Summary: TB domain
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This domain is also known as the 8 cysteine domain. This family includes the hybrid domains . This cysteine rich repeat is found in TGF binding protein and fibrillin.
Pereira L, D'Alessio M, Ramirez F, Lynch JR, Sykes B, Pangilinan T, Bonadio J; , Hum Mol Genet 1993;2:961-968.: Genomic organization of the sequence coding for fibrillin, the defective gene product in Marfan syndrome. PUBMED:8364578 EPMC:8364578
Yuan X, Downing AK, Knott V, Handford PA , EMBO J 1997;16:6659-6666.: Solution structure of the transforming growth factor beta-binding protein-like module, a domain associated with matrix fibrils. PUBMED:9362480 EPMC:9362480
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR017878
The transforming growth factor beta family of cytokines, are potent and multifunctional signalling molecules. Prior to ligand receptor binding there exist extracellular regulators that target these cytokines and facilitate the formation of morphogen gradients that control developmental processes. Some of these proteins that are known to sequester latent TGF-beta contains a conserved domain, the TGF-beta binding (TB) domain.
The domain is characterised by 8 conserved cysteine residues, which include an unusual cysteine triplet [PUBMED:9362480, PUBMED:14607119]. The TB fold is globular with six beta-strands and two alpha-helices [PUBMED:9362480, PUBMED:14607119, PUBMED:15062093]. The pairing of the eight cysteines is 1-3, 2-6, 4-7, and 5-8, creating a fairly rigid structure. In follistatin and in the first repeat of fibrillin and LTBPs the last disulphide bridge is absent.
Proteins containing a TB domain include:
- Vertebrate fibrillin-1, 2 and 3. Fibrillins form tissue-specific and temporally regulated microfibril networks. They are implicated in the regulation of TGF-beta signalling.
- Vertebrate latent TGF-beta binding proteins (LTBPs) 1, 2, 3 and 4 LTBPs regulate TGF-beta signalling by forming a latent complex with the cleaved TGF-beta proproteins.
- Vertebrate follistatin. It is an extracellular antagonist of various TGF-beta proteins. The TB domain of follistatin mimic a type I receptor of TGF-beta and binds TGF-beta which leads to the formation of a receptor-ligand-antagonist complex [PUBMED:16198295].
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a textual description of the architecture, e.g. Gla, EGF x 2, Trypsin.
This example describes an architecture with one
Gladomain, followed by two consecutive
EGFdomains, and finally a single
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We make a range of alignments for each Pfam-A family:
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Curation and family details
|Seed source:||Pfam-B_82 (release 2.1)|
|Number in seed:||274|
|Number in full:||3137|
|Average length of the domain:||41.30 aa|
|Average identity of full alignment:||37 %|
|Average coverage of the sequence by the domain:||11.69 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 80369284 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||13|
|Download:||download the raw HMM for this family|
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There are 2 interactions for this family. More...
We determine these interactions using iPfam, which considers the interactions between residues in three-dimensional protein structures and maps those interactions back to Pfam families. You can find more information about the iPfam algorithm in the journal article that accompanies the website.
For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the TB domain has been found. There are 9 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.
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