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10 Cards in this Set
- Front
- Back
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How many different types of collagens are there?
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19 (XIX)
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What are the functional classifications of collagens?
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Fibril forming (I, II, III, V and XI)
Network forming (IV, VIII and X) Associated with fibril surfaces (IX, XII and XIV) Transmembrane (XIII and XVII) Endostatin forming (XV and XVIII) Beaded filaments (VI) |
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What are the common structural characteristics of the fibrous collagens (I, II and III)?
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Each polypeptide chain has about 1,000 amino acids. Each chain is called an alpha chain. Mature collegen has three alpha chains, and every third amino acid is a glycine. Collagen contains about 20% proline and hydroxyproline, and 1-5% hydroxylysine. Each alpha chain froms a proline helix.
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How is the collagen helix different then the alpha helix?
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More extended; does not have intrachain hydrogen bonds; stabilized by steric repulsion of the pyrrolidone rings; essential a tertiary structure.
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What are some important features of the collagen triple helix?
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Rod-shaped, with a length of 3000A and a width of 15A. Glycine is found at the interface between the three chains -- it is the only side chain small enough to fit at this interface. The three collagen strands are hydrogen bonded to each other via the peptide NH of glycine residues and the peptide CO of other residues. Hydroxyproline also participates in interchain H-bonds.
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What co-factor is required for the hydroxylation of proline and lysine?
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Vitamin C (ascorbic acid)
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What are the steps to mature collagen formation?
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Translation from mRNA, hydroxylation and glycosylation, intiation of triple helix formation, procollagen, secretion and processing, tropocollagen, packing, collagen fibril, crosslinking
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What is the key step to crosslinking of collagen fibrils?
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The enzymatic formation of aldehyde derviatives of lysine and hydroxylysine. Subsequent crosslinking is non-enzymatic and involves reaction between lysyl and allysl groups
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What is elastin?
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Found in elastic fibers in the ECM of tissues such as smooth muscle. Alternating hydrophilic and hydrophobic regions to allow stretching and then returning. Contain microfibrils composed of proteins such as fibrillin-1 and fibrillin-2.
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What is laminin?
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Binds to and crosslinks other proteins in the basal lamina. Heterotrimeric with alpha, beta, and gamma subunits. Helical regions in each subunit form a triple helix association domain. All three subunits have N-terminal globular extensions; alpha subunit also has a C-terminal globular domain.
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