Biochem: Matrix Proteins Flashcards
Type of collagen found in blood vessels and fetal skin.
Type III
Type of collagen found in skin, bone, tendon, blood vessels, cornea
Type I
Type of collagen found in basement membranes.
Type IV
Type of collagen found in cartilage, IV disc, and virtreous body
Type II
Role of Vitamin C in collagen synthesis.
Co-factor for hydroxylation of proline and lysine residues
-the OH functional groups allow hydrogen bonding between helices of collagen units to make the structure stronger
Pathogenesis of Menkes Syndrome
X-linked recessive mutation in Copper-Binding ATPase
- prevents adequate uptake of copper from the diet
- copper is needed for the enzyme lysine oxidase, without it tropocollagen units do not cross-link well and the patient usually dies in infancy
Pathogenesis of Osteogenesis Imperfecta.
Autosomal dominant mutation in genes required for Type 1 collagen production. Type 1 collagen is either absent or in reduced amounts. Characteristic blue sclera (blue color comes from blood in the choroid veins, the sclera is thinner in this disease making the color more visible)
Mildest form and most severe form of Osteogenesis Imperfecta.
Mildest: Type 1
Most severe: Type 2
Pathogenesis of the most common type of Ehlers Danlos Syndrome.
Type 3
- mutation in the gene encoding Tenascin-X
- results in Hypermobile Joints
Pathogenesis of Type 1 and 2 Ehlers Danlos
Abnormal Type V collagen formation
Pathogenesis of Type 4 Ehlers Danlos
Mutation in genes encoding Type III collagen
-vascular condition with a high risk of blood vessel rupture
Pathogenesis of Dystrophic Epidermolysis Bullosa (DEB).
Mutation in the gene that encodes Type VII collagen resulting in blisters and breaks in the skin
Pathogenesis of Alport Syndrome.
Gene mutation in Type IV collagen production
-leads to abnormal formation of basement membranes
(multiple genes can mutate and result in this condition)
Major complication of Alport Syndrome
Renal Failure in early adult life
Component of elastin connective tissue that gives it strength.
Cross-linking of lysine residues in elastin chains forming structures called Desmosines
Major complication and pathogenesis of William Syndrome.
Supravalvular Aortic Stenosis
- deletion of multiple genes on Chromosome 7
- results in a deficiency of elastin causing unstable blood vessels
- other sequelae include: elfin facial appearance, very trusting personality
Complication of Alpha-1 Antitrypsin deficiency.
Emphysema
- the enzyme is needed to inactivate elastases
- without A-1A, elastases are overactive and degrade elastin in alveolar tissue
Main connective tissue function of Fibrillin
Polymerizes to form scaffolding for elastin deposition
Gene mutated in Marfan Syndrome
Fibrillin-1 gene
Main function of Fibronectin.
Component of the extracellular matrix that “glues” cells together
Obstetric application for Fibronectin
Fetal Fibronectin Test
- fibronectin is used to hold the amniotic sac to the uterus in pregnancy
- if fetal fibronectin levels are raised from a cervical swab, it could indicate higher risk of preterm labor
Pathogenesis of Junctional Epidermolysis Bullosa.
Defect in laminin in skin
- results in instability of the dermoepidermal junction
- blistering of skin and mucous membranes
Pathogenesis of Congenital Muscular Dystrophy.
Defect in laminin in muslces
- results in instability of the muscle cell cytoskeleton-extracellular matrix link
- muscle weakness
Most abundant Glycosaminoglycan (GAG)
Chondroitin Sulphate
-present in cartilage, tendon, bone, ligaments, cornea
GAG that plays a role in corneal transparency
Keratan Sulphate I
GAG involved in anticoagulation
Heparin
GAG involved in synovial fluid of joints and vitreous humor
Hyaluronic Acid
General Pathogenesis of Mucopolysaccharidoses
Deficiency in lysosomal enzymes that degrade GAGs
Mucopolysaccharidosis that involves corneal clouding, stiff joints, Aortic Valve disease, normal intelligence, and normal lifespan
Scheie Syndrome
Mucopolysaccharidosis that involves mental retardation, corneal clouding, dwarfing, and early death due to depositions in coronary arteries
Hurler Syndrome
Mucopolysacharidosis that involves mental retardation, physical deformity, no corneal clouding
Hunter Syndrome
