ECM
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Questions and Answers

Which protein is NOT a type of ECM proteins?

  • Structural proteins:
  • Specialized proteins
  • Proteoglycans
  • Tropocollagen (correct)

    • Match the protein type to its proteins

    Structural proteins = Collagen, Elastin, Fibrillin Specialized proteins = Fibronectin, Laminin Proteoglycans = GAGs x = x

    What is needed for the synthesis of Collagen

    Fibroblasts

    What is the structural unit of collagen?

    <p>Tropocollagen</p> Signup and view all the answers

    What does collagen mainly consist of?

    <p>Proline, Hydroxyproline (sometimes Lysine and Hydroxylysine)</p> Signup and view all the answers

    Why does collagen have a very firm structure?

    <p>2H E 2F S - High content of glycine, hydroxyproline - Each turn contains only 3 aa —&gt; tight helix - Formation of right handed superhelix, covalent cross links between th adjacent polypeptide chains - Specific arrangement into fibrils, fibers</p> Signup and view all the answers

    What is the first step to the synthesis of collagen?

    <p>Synthesis of preprocollagen a chains</p> Signup and view all the answers

    How does the first step in the intracellular synthesis of collagen end?

    <p>Signal peptide directs chain to ER</p> Signup and view all the answers

    What happens in the second step in the intracellular synthesis of collagen?

    <p>Removal of signal peptide by signal peptidase. Hydroxylation of proline and lysine residues. Glycosylation of hydroxylysyl residues by addition of glucose and galactose</p> Signup and view all the answers

    How does the intracellular synthesis of collagen end?

    <p>Exocytosis of the procollagen</p> Signup and view all the answers

    How does the formation of tropocollagen from procollagen proceed?

    <p>Removal of N extension peptide (aminoproteinase) removal of C extension peptide(carboxyproteinase)</p> Signup and view all the answers

    How do the interchain cross links form?

    <p>By lysyl oxidase (contains Cu2+)</p> Signup and view all the answers

    What does a genetic defect in collagen lead to?

    <p>Osteogenesis imperfecta syndrome</p> Signup and view all the answers

    What is the cause of Osteogenesis imperfecta aka Brittle bone syndrome

    <p>Replacement of glycine by amino acid with bulky side chain</p> Signup and view all the answers

    Which answer does not correctly state the manifestations of Osteogenesis imperfecta?

    <p>Easy bone fracture, loose joints, poor muscle tone, slight spinal curve</p> Signup and view all the answers

    What is the cause of Ehlers Danlos syndrome?

    <p>Partial deficiency of procollagen. peptidases —&gt; procollagen not fully converted to tropocollagen</p> Signup and view all the answers

    What are the manifestations of Ehlers Danlos syndrome?

    <p>Short stature, stretchable skin, hypermobile joints</p> Signup and view all the answers

    What is the cause of Lathyrism?

    <p>Inhibition of lysyl oxidase by ingestion of sweet pea seeds / copper deficiency which is needed for lysyl oxidase</p> Signup and view all the answers

    What are the manifestations of Lathyrism?

    <p>3D JA: Deformation of spine, dislocation of joints, demineralization of bone, joint hemorrhage, aortic aneurysm</p> Signup and view all the answers

    Elastin is a … like protein

    <p>rubber</p> Signup and view all the answers

    Where is collagen found in the body?

    <p>Skin, bone, cartilage, tendons, ligaments, blood vessels, cornea</p> Signup and view all the answers

    Where is elastin found in the body?

    <p>Ligaments, lungs, wall of blood vessels</p> Signup and view all the answers

    What is the main unit of elastin?

    <p>Tropoelastin</p> Signup and view all the answers

    Why does elastin have elastic properties?

    <p>3 allysine residues interact with 1 unoxidized lysine to form desmosine.</p> Signup and view all the answers

    What is the shape of elastin?

    <p>Fibrous when extended and globular when relaxed</p> Signup and view all the answers

    What is the importance of a-1 anti-trypsin deficiency?

    <p>Protects tissues from elastase enzymes from inflammatory cells (neutrophils)</p> Signup and view all the answers

    Why do proteinases like trypsin and elastase get secreted?

    <p>When the body reacts to acute inflammation (bacterial infection), the inflammatory cells secrete proteinases.</p> Signup and view all the answers

    What happens in the absence of a-1 anti-trypsin?

    <p>Neutrophil elastase breaks down elastin, damages lung elasticity, causing respiratory complications.</p> Signup and view all the answers

    What is fibronectin?

    <p>Major protein of the ECM</p> Signup and view all the answers

    Where is fibronectin found?

    <p>Connective tissue, plasma</p> Signup and view all the answers

    What is fibronectin's structure?

    <p>2 subunits (identical) connected by a 2 disulfide bond, also has several binding sites.</p> Signup and view all the answers

    What does fibronectin bind with?

    <p>Heparin, collagen, cell surface receptors (integrin)</p> Signup and view all the answers

    What is fibronectin's importance?

    <p>It has adhesive characteristics which allows it to adhere with transmembrane receptors like integrin.</p> Signup and view all the answers

    What is fibronectin glomerulopathy?

    <p>Mutation of the gene coding fibronectin.</p> Signup and view all the answers

    What are the effects of fibronectin glomerulopathy?

    <p>Abnormal fibronectin in glomeruli of kidneys, leading to abnormal glomerular structures/functions.</p> Signup and view all the answers

    What are the manifestations of fibronectin glomerulopathy?

    <p>Hematuria, proteinuria, hypertension, renal tubular acidosis, renal failure.</p> Signup and view all the answers

    What is fibrillin?

    <p>Glycoprotein secreted into ECM by fibroblasts.</p> Signup and view all the answers

    Where is fibrillin found?

    <p>Suspensory ligaments of lens, aorta.</p> Signup and view all the answers

    What is the importance of fibrillin?

    <p>Forms scaffold for deposition of elastin.</p> Signup and view all the answers

    What is the cause of Marfan’s syndrome?

    <p>Mutation of gene encoding for fibrillin.</p> Signup and view all the answers

    What are the manifestations of Marfan’s syndrome?

    <p>Dislocation of lens, dilatation of aorta, hyperextensibility of joints.</p> Signup and view all the answers

    What are cartilage proteins and how are they classified?

    <p>Cartilage is avascular CT and classified into collagen and non-collagenous proteins.</p> Signup and view all the answers

    What is the main collagen protein?

    <p>Collagen type II.</p> Signup and view all the answers

    What is collagen type II?

    <p>It’s 98% of total collagen in cartilage and contains more hydroxylysine and glycosylation.</p> Signup and view all the answers

    What is the most important non-collagenous protein in cartilage?

    <p>Proteoglycans (aggrecans), contains KCH (GAGs).</p> Signup and view all the answers

    What do the GAGs in cartilage look like?

    <p>The 3 are attached to a core protein and have a bottle brush appearance.</p> Signup and view all the answers

    Who is the binder in cartilage proteins?

    <p>Chondronectin binds type II collagen.</p> Signup and view all the answers

    What are bone proteins and how are they classified?

    <p>Mineralized CT and classified into collagen and non-collagenous proteins.</p> Signup and view all the answers

    What is the most important collagen protein in bone proteins?

    <p>Collagen type I (90% of total collagen in bone).</p> Signup and view all the answers

    What is the major non-collagenous protein in bone proteins?

    <p>Osteocalcin.</p> Signup and view all the answers

    Who is the binder in bone proteins?

    <p>Osteonectin binds collagen.</p> Signup and view all the answers

    What is osteoporosis?

    <p>Progressive reduction of bone mass/density.</p> Signup and view all the answers

    What are risk factors of osteoporosis?

    <p>Aging, Female, Family history, Sedentary life, Intake of caffeine and soda, Low intake of Ca/Mg/Vitamin D, Smoking, Drugs like corticosteroids.</p> Signup and view all the answers

    Which protein is NOT a Glycoprotein?

    <p>Elastin</p> Signup and view all the answers

    Match the protein with its common sites

    <p>Collagen = Skin, bone, cartilage, tendons, liver, lungs, vessels, cornea Elastin = Ligaments, lung and blood vessels Fibrillin = Suspensory ligaments of lens, aorta Fibronectin = ECM and Plasma</p> Signup and view all the answers

    Match the protein with its structure

    <p>Collagen = Tropocollagen stabilized by hydrogen bond and covalent cross links Elastin = Tropoelastin stabilized by desmosine cross links Fibrillin = Cysteine rich motifs stabilized by disulfide bonds Fibronectin = 2 identical polypeptide chains connected by disulfide bonds</p> Signup and view all the answers

    Match the protein with its function

    <p>Collagen = Supportive Elastin = Elasticity Fibronectin = Adhesion Fibrillin = Scaffold for deposition of elastin and tensile strength in nonelastic tissues</p> Signup and view all the answers

    Match the protein with its disorders

    <p>Collagen = Osteogenesis imperfecta, Ehlers Danlos, Lathyrism, Scurvy, Tissue fibrosis Elastin = a-1 anti-trypsin deficiency Fibrillin = Marfan Syndrome Fibronectin = Fibronectin glomerulopathy</p> Signup and view all the answers

    Study Notes

    Collagen & Elastin

    • Collagen is found in various tissues, including skin, bone, cartilage, tendons, ligaments, blood vessels, and cornea.
    • Elastin is found in ligaments, lungs, and the walls of blood vessels.
    • Tropoelastin is the main unit of elastin.
    • Elastin's elastic properties stem from the formation of desmosine, a molecule created from the interaction of three allysine residues and one unoxidized lysine.
    • Elastin exhibits fibrous shape when extended and a globular shape when relaxed.

    α-1 Antitrypsin Deficiency

    • α-1 antitrypsin is a protein that protects tissues from elastase enzymes released by inflammatory cells like neutrophils.
    • During acute inflammation, such as bacterial infection, the body releases proteinases like trypsin and elastase.
    • In the absence of α-1 antitrypsin, neutrophil elastase breaks down elastin, damaging lung elasticity and leading to respiratory complications like emphysema, COPD, and cirrhosis of the liver.

    Fibronectin

    • Fibronectin is a major protein of the extracellular matrix (ECM).
    • It's found in connective tissue and plasma.
    • Fibronectin consists of two identical subunits connected by two disulfide bonds and has several binding sites.
    • It binds to heparin, collagen, and cell surface receptors like integrin.
    • Fibronectin's adhesive characteristics allow it to bind to transmembrane receptors like integrin, contributing to cell communication between the extracellular and intracellular environments.
    • Fibronectin glomerulopathy is a genetic disorder caused by a mutation in the fibronectin gene, leading to abnormal fibronectin production in kidney glomeruli and impaired glomerular function.
    • Fibronectin glomerulopathy can manifest as hematuria, proteinuria, hypertension, renal tubular acidosis, and renal failure.

    Fibrillin

    • Fibrillin is a glycoprotein secreted into the ECM by fibroblasts.
    • It is found in the suspensory ligaments of the lens and the aorta.
    • Fibrillin forms the scaffold for elastin deposition.
    • Marfan syndrome is caused by a mutation in the gene encoding fibrillin, leading to various complications.
    • Marfan syndrome can lead to lens dislocation, aortic dilation, and joint hyperextensibility.

    Cartilage Proteins

    • Cartilage is avascular connective tissue containing collagen and non-collagenous proteins.
    • Collagen type II is the main collagen protein in cartilage, accounting for 98% of the total collagen content.
    • Proteoglycans, particularly aggrecans containing glycosaminoglycans (GAGs), are the most important non-collagenous proteins in cartilage.
    • GAGs in cartilage have a bottle brush appearance, with three GAGs attached to a core protein.
    • Chondronectin, a binder protein, binds to type II collagen in cartilage.

    Bone Proteins

    • Bone is mineralized connective tissue containing collagen and non-collagenous proteins.
    • Collagen type I is the most important collagen protein in bone, making up 90% of the total collagen content.
    • Osteocalcin is the major non-collagenous protein in bone.
    • Osteonectin, a binder protein, binds to collagen in bone.

    Osteoporosis

    • Osteoporosis is a progressive condition characterized by reduced bone mass and density.
    • Risk factors for osteoporosis include: aging, female sex, family history, sedentary lifestyle, caffeine and soda consumption, low intake of calcium, magnesium, and vitamin D, smoking, and corticosteroid use.

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