5nb2 | pdb_00005nb2
Crystal structures of homooligomers of collagen type IV. alpha2NC1
Structural highlights
DiseaseCO4A2_HUMAN Defects in COL4A2 are the cause of porencephaly type 2 (POREN2) [MIM:614483. POREN2 is a neurologic disorder characterized by a fluid-filled cysts or cavities within the cerebral hemispheres. Affected individuals typically have hemiplegia, seizures, and intellectual disability. Porencephaly type 2, or schizencephalic porencephaly, is usually symmetric and represents a primary defect in the development of the cerebral ventricles.[1] Defects in COL4A2 are a cause of susceptibility to intracerebral hemorrhage (ICH) [MIM:614519. ICH is a pathological condition characterized by bleeding into one or both cerebral hemispheres including the basal ganglia and the cerebral cortex. It is often associated with hypertension and craniocerebral trauma. Intracerebral bleeding is a common cause of stroke.[2] FunctionCO4A2_HUMAN Type IV collagen is the major structural component of glomerular basement membranes (GBM), forming a 'chicken-wire' meshwork together with laminins, proteoglycans and entactin/nidogen.[3] [4] [5] Canstatin, a cleavage product corresponding to the collagen alpha 2(IV) NC1 domain, possesses both anti-angiogenic and anti-tumor cell activity. It inhibits proliferation and migration of endothelial cells, reduces mitochondrial membrane potential, and induces apoptosis. Specifically induces Fas-dependent apoptosis and activates procaspase-8 and -9 activity. Ligand for alphavbeta3 and alphavbeta5 integrins.[6] [7] [8] Publication Abstract from PubMedBasement membranes are extracellular structures of epithelia and endothelia that have collagen IV scaffolds of triple alpha-chain helical protomers that associate end-to-end, forming networks. The molecular mechanisms by which the noncollagenous C-terminal domains of alpha-chains direct the selection and assembly of the alpha1alpha2alpha1 and alpha3alpha4alpha5 hetero-oligomers found in vivo remain obscure. Autoantibodies against the noncollagenous domains of the alpha3alpha4alpha5 hexamer or mutations therein cause Goodpasture's or Alport's syndromes, respectively. To gain further insight into oligomer-assembly mechanisms as well as into Goodpasture's and Alport's syndromes, crystal structures of non-collagenous domains produced by recombinant methods were determined. The spontaneous formation of canonical homohexamers (dimers of trimers) of these domains of the alpha1, alpha3 and alpha5 chains was shown and the components of the Goodpasture's disease epitopes were viewed. Crystal structures of the alpha2 and alpha4 non-collagenous domains generated by recombinant methods were also determined. These domains spontaneously form homo-oligomers that deviate from the canonical architectures since they have a higher number of subunits (dimers of tetramers and of hexamers, respectively). Six flexible structural motifs largely explain the architectural variations. These findings provide insight into noncollagenous domain folding, while supporting the in vivo operation of extrinsic mechanisms for restricting the self-assembly of noncollagenous domains. Intriguingly, Alport's syndrome missense mutations concentrate within the core that nucleates the folding of the noncollagenous domain, suggesting that this syndrome, when owing to missense changes, is a folding disorder that is potentially amenable to pharmacochaperone therapy. Structures of collagen IV globular domains: insight into associated pathologies, folding and network assembly.,Casino P, Gozalbo-Rovira R, Rodriguez-Diaz J, Banerjee S, Boutaud A, Rubio V, Hudson BG, Saus J, Cervera J, Marina A IUCrJ. 2018 Oct 10;5(Pt 6):765-779. doi: 10.1107/S2052252518012459. eCollection, 2018 Nov 1. PMID:30443360[9] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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