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collagen type-1

Function: - see collagen - collagen fibers are a major component of extracellular matrix - great tensile strength - gives bone its elasticity & contributes to fracture resistance. - facilitates formation of bone from cartilage; 40 nm gaps between the ends of the tropocollagen subunits probably serve as nucleation sites for the deposition of long, hard, fine crystals of the mineral component, hydroxyapatite - end product when tissue heals by repair - associates with type-5 collagen & type-6 collagen Structure: - in bone, entire collagen triple helices lie in a parallel, staggered array Expression: - most abundant collagen of the human body - skin - scar tissue - tendons - endomysium of myofibrils - fibrocartilage - organic part of bone 95% of collagen in bone is type 1 - expression of type 1 procollagen is enhanced by activity of the TGF-beta/Smad/CTGF axis; TGF-beta & CTGF independently stimulate type 1 procollagen expression [4] Pathology: 1) defects in type-1 collagen associated with a) osteogenesis imperfecta b) Ehlers-Danlos Syndrome c) also see collagen 2) diminished production of type 1 procollagen by fibroblasts occurs with chronological aging of human skin via downregulation of the TGF-beta/Smad/CTGF axis [4] Notes: Formation of collagen type-1 (most collagens are formed similarly) 1) intracellular a) 3 peptide chains are formed (2 COL2A1 & 1 COL1A2) in ribosomes along the rough endoplasmic reticulum (ER) these peptide chains (preprocollagen); each chain has registration peptides on each end & a signal peptide b) preprocollagen chains are translocated into the lumen of the ER via N-terminal signal peptides c) signal Peptides are cleaved inside the RER (procollagen) d) hydroxylation of Lys & Pro occurs in the ER lumen. process is dependent on ascorbate (vit C) as a cofactor e) O-glycosylation of specific hydroxy amino acid residues f) triple helical structure is formed inside the ER g) procollagen is shipped to the GOLD, where it is packaged & secreted by exocytosis 2) extracellular a) registration peptides are cleaved & tropocollagen is formed by procollagen peptidase b) multiple tropocollagen molecules form collagen fibrils, & multiple collagen fibrils form into collagen fibers c) collagen is attached to cell membranes via several types of protein, including fibronectin & integrins

Related

procollagen type 1 in serum

General

collagen

Properties

COMPARTMENT: extracellular matrix WITHIN: skin bone tendon SECRETED-BY: fibroblast SUBUNITS: collagen 1 alpha-1 (2) MOTIF: signal sequence {1-22} VWFC domain {38-96} proteolytic site {161-162} Nonhelical region {162-178} Triple-helical region {179-1192} MOTIF: Cell attachment {745-747} proteolytic site {953-954} Cell attachment {1093-1095} Nonhelical region {1193-1218} proteolytic site {1218-1219} Fibrillar collagen NC1 {1229-1464} MOTIF: cysteine residue {C1259} MODIFICATION: cysteine residue {C-INTERCHAIN} cysteine residue {C1265} MODIFICATION: cysteine residue {C-INTERCHAIN} cysteine residue {C1282} MODIFICATION: cysteine residue {C-INTERCHAIN} cysteine residue {C1291} MODIFICATION: cysteine residue {C-INTERCHAIN} cysteine residue {C1299} MODIFICATION: cysteine residue {C1462} N-glycosylation site {N1365} cysteine residue {C1370} MODIFICATION: cysteine residue {C1415} cysteine residue {C1415} MODIFICATION: cysteine residue {C1370} cysteine residue {C1462} MODIFICATION: cysteine residue {C1299} collagen 1 alpha-2 MOTIF: signal sequence {1-24} Fibrillar collagen NC1 {1133-1366} MOTIF: N-glycosylation site {N1267}

References

  1. Molecular Cell Biology (2nd ed) Darnell J; Lodish H & Baltimore D (eds), Scientific American Books, WH Freeman, NY 1990, pg 906
  2. Greendale, Multicampus Program in Geriatrics & Gerontology, 2001
  3. Wikipedia, collagen entry http://en.wikipedia.org/wiki/collagen
  4. Quan T et al. Reduced expression of connective tissue growth factor (CTGF/CCN2) mediates collagen loss in chronologically aged human skin. J Invest Dermatol 2010 Feb; 130:415. PMID: 19641518

Components

collagen 1 alpha-1; collagen alpha-1(I) chain; alpha-1 type I collagen (COL1A1) collagen 1 alpha-2 (COL1A2)