Summary: G2F domain
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Nidogen, an invariant component of basement membranes, is a multifunctional protein that interacts with most other major basement membrane proteins. The G2 fragment or (G2F domain) contains binding sites for collagen IV and perlecan. The structure is composed of an 11-stranded beta-barrel with a central helix. This domain is structurally related to that of green fluorescent protein PF01353. A large surface patch on the beta-barrel is conserved in all metazoan nidogens.
Hopf M, Gohring W, Ries A, Timpl R, Hohenester E; , Nat Struct Biol 2001;8:634-640.: Crystal structure and mutational analysis of a perlecan-binding fragment of nidogen-1. PUBMED:11427896 EPMC:11427896
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This tab holds annotation information from the InterPro database.
InterPro entry IPR006605
Basement membranes are sheet-like extracellular matrices found at the basal surfaces of epithelia and condensed mesenchyma. By preventing cell mixing and providing a cell-adhesive substrate, they play crucial roles in tissue development and function. Basement menbranes are composed of an evolutionarily ancient set of large glycoproteins, which includes members of the laminin family, collagen IV, perlecan and nidogen/entactin. Nidogen/entactin is an important basement membrane component, which promotes cell attachment, neutrophil chemotaxis, trophoblast outgrowth, and angiogenesis. It consists of three globular regions, G1-G3. G1 and G2 are connected by a thread-like structure, whereas that between G2 and G3 is rod-like [PUBMED:9633511, PUBMED:11427896].
The nidogen G2 region binds to collagen IV and perlecan. The nidogen G2 structure is composed of two domains, an N-terminal EGF-like domain and a much larger beta-barrel domain of ~230 residues. The nidogen G2 beta-barrel consists of an 11-stranded beta-barrel of complex topology, the interior of which is traversed by the hydrophobic, predominantly alpha helical segment connecting strands C and D. The N-terminal half of the barrel comprises two beta-meanders (strands A-C and D-F) linked by the buried alpha-helical segment. The polypeptide chain then crosses the bottom of the barrel and forms a five-stranded Greek key motif in the C- terminal half of the domain. Helix alpha3 caps the top of the barrel and forms the interface to the EGF-like domain. The nidogen G2 beta-barrel domain has unexpected structural similarity to green fluorescent protein, suggesting that they derive from a common ancestor. A large surface patch on the barrel surface is strikingly conserved in all metazoan nidogens. Site-directed mutagenesis demonstrates that the conserved residues in the conserved patch are involved in the binding of perlecan, and possibly also of collagen IV [PUBMED:11427896].
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This superfamily has an unusual fold of an 11 stranded beta barrel enclosing an alpha-helix. This superfamily includes green fluorescent protein as well as a domain from nidogen.
The clan contains the following 2 members:G2F GFP
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Curation and family details
|Seed source:||Bateman A|
|Number in seed:||5|
|Number in full:||296|
|Average length of the domain:||182.50 aa|
|Average identity of full alignment:||35 %|
|Average coverage of the sequence by the domain:||9.46 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||7|
|Download:||download the raw HMM for this family|
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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 G2F domain has been found. There are 2 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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