Mindmap

Glycoconjugates

Valentina Ardila Mora Medicina Englisch

Inhalt der Mindmap

Glycoconjugates

one or more carbohydrate chains
- covalently linked to protein or lipid
Glycoproteins
- Contain
  - oligosaccharide chains
    - glycosylation pattern depends on
      - pattern of expression of glycosyltransferases
        glycoprotein synthesis
      - affinity of glycosyltransferases for substrates
        substrate for glycoprotein synthesis
        corresponding sugar nucleotide
        UDP uridine diphosphate
        GDP guanosine diphosphate
        CMP cytidine monophosphate
      - relative availability of carbohydrate substrates
    - 8 carbohydrate molecules
      - glucose
      - galactose
      - mannose
      - fructose
      - xylose
      - N-acetylgalactosamine GalNAc
      - N-acetylglucosamine
      - N-acetylneuraminic acid NeuAc
        termini of oligosaccharide chains
    - sulfate often found in glycoproteins
      - attached to
        N-acetylglucosamine
        N-acetylgalactosamine
    - 1-30 or more chains
    - Form
      - linear
      - branched
  - amino acid
- sugar attachment
  - glycosylation
    - enzymic
  - glycation
    - Nonenzymic
- Main types
  - O-glycosidic linkage
    - amino acid hydroxyl groups
      - modified residues
        hydroxyproline
        hydroxylysine
      - threonine
      - serine
    - N-acetylgalactosamine
    - subclasses
      - N-acetylgalactosamine-Ser(Thr)
        N-acetylgalactosamine linked to
        galactose
        N-acetylneuraminic acid
        found in mucins
      - Proteoglycans
        galactose-galactose-xylose trisaccharide
        attached to serine
      - Collagens
        galactose-hydroxylysine linkage
      - nuclear and cytosolic proteins
        single N-acetylglucosamine attached to residues
        serine
        threonine
  - N-glycosidic linkage
    - N-acetylglucosamine
      - usually poly-N-acetyllactosaminoglycans
    - asparagine
      - amino group
    - Location
      - bound to membrane
      - circulating
    - Classes
      - Man3GlcNAc2 bound to asparagine
        differ in outer branches
        complex
        2-5 outer branches (antennae)
        terminate in
        galactose
        fucose
        blood group substances
        high-mannose
        2-6 additional mannose residues
        hybrid
        features of both classes.
  - glycosylphosphatidylinositol (GPI) linkage
    - N-acetylglucosamine
      - link a glycan chain with a variety of sugars
        linked via phosphorylethanolamine
        to the carboxyl-terminal amino acid
    - phosphatidylinositol (PI)
      - link proteins to membrane's luminal leaflet
    - Functions
      - polarized epithelial cells
        direct glycoproteins to plasma membrane
        basolateral
        apical
      - enhanced protein mobility in the membrane
        GPI anchor attached only to outer leaflet
        freer to diffuse
        facilitating rapid responses to stimuli.
      - signal transduction pathways
        proteins without transmembrane domain
        receptors for
        hormones
        other cell surface signals
    - commonly anchored to cell membranes
- Biochemical Roles
  - Mucins
    - Location
      - Lungs
      - saliva
      - digestive tract
      - connective tissue
    - Functions
      - Lubrication
        lungs
        connective tissue
      - protection from bacterial invasion
        digestive tract
    - Increased
      - Cancers
        pancreas
        lung
        breast
        ovary
        colon
      - lung diseases
        asthma
        bronchitis
        chronic obstructive pulmonary disease
        cystic fibrosis
    - Decreased
      - cause ulcerative colitis
  - Antibodies & major histocompatability complex
    - Location
      - White blood cells
    - Functions
      - Specific glycosylated proteins
        recognition/ activation molecules for immune cells
  - Glycoprotein IIb/IIIa
    - Location
      - Platelets
    - Functions
      - Platelet aggregation
      - clot formation
    - Deficiency
      - bruising/ bleeding problems
        Glanzmann’s thrombasthenia
        idiopathic thrombocytopenic purpura
  - Transferrin
    - Location
      - Blood
    - Function
      - Iron transport
  - ceruloplasmin
    - Location
      - Blood
    - Function
      - copper transport
  - Calnexin & calreticulin
    - Location
      - Endoplasmic reticulum
    - Function
      - newly synthesized glycoproteins
        Ensure proper
        folding
        glycosylation
  - Notch glycoproteins (receptors)
    - Locations
      - Nerve
      - arteries
      - heart
      - pancreas
      - intestines
      - bone
      - mammary glands
      - cytoskeleton
    - Functions
      - cell development
      - dierentiation in many tissues
    - Alterations cause
      - multiple sclerosis
      - Tetralogy of Fallot
      - Alagille syndrome
      - certain leukemias
  - glycoprotein receptors and membrane-bound molecules
    - Location
      - Sperm egg interaction
        glycoprotein ZP3
        O-linked glycoprotein
        acts as sperm receptor
        acrosomal reaction
        sperm passes zona pellucida
      - virus coats
        attachment to infect host cells
      - bacterial coats
      - lectins
        selectins
        bind sialylated & fucosylated oligosaccharides
        found in
        Leukocytes
        neutrophils
        activated
        endothelial cells
        cancer cells
        metastasis
        invasion
        carbohydrate-binding proteins (some are glycoproteins)
        not Immunoglobulins
        at least 2 sugar-binding sites
        Function
        precipitate glycoconjugates
        agglutinate cells
        purify glycoproteins
        probing the glycoprotein profiles of cell surfaces,
        reagents for generating mutant cells deficient in certain enzymes
        Example
        asialoglycoprotein receptor
        Liver cells
        recognizes galactose moiety
        from desialylated plasma proteins
        endocytosis and catabolism
        Found in
        animals
        plants
        phytohemagglutinins
        agglutinate red blood cells
        undercooked legumes
        Undenatured lectins
        agglutinating the mucosal cells
        stripping of the intestinal mucosa
        microorganisms
      - drugs
      - hormones
    - Functions
      - cell recognition
      - cell attachment
      - initiation of biological processes by signaling
  - Hormones
    - Follicle-stimulating hormone
    - luteinizing hormone
    - thyroid-stimulating hormone
    - human chorionic gonadotropin
    - α-fetoprotein
    - erythropoietin
  - collagens
    - Structural molecule
Glycolipids
- lipids with an attached carbohydrate or carbohydrate chain
  - mostly in outer leaflet of the plasma membrane
    - glycocalyx
  - human glycolipid
    - glycerol backbone
      - generally replaced by sphingosine backbone
        made from
        palmitate
        serine
        Sphingolipid
        remaining hydroxyl (OH) group
        amino (NH3 ) group
        bound to another fatty acid
        ceramide
        molecules bind to the ceramide hydroxyl (OH)
        carbohydrate molecules
        glycosphingolipid
        Cerebrosides
        Ceramide attached to
        1 glucose residue
        glucosylceramide
        the most predominant in extraneural tissues
        1 galactose residue
        galactosylceramide
        C24 fatty acids
        cerebronic acid.
        converted to
        sulfogalactosylceramide in myelin
        plasma membranes
        muscle
        nerve cells
        myelin
        covers nerve axons
        for conduction of nerve impulses
        fast
        efficient
        opiates binding
        Sulfatides
        Galactose-based glycosphingolipid molecules
        SO4−2 in place of the phosphorous
        mainly in
        nervous system
        central
        peripheral
        Functions
        Regulate
        cell growth
        cell signaling
        affect Na & K transportation in cells
        platelets
        blood clots
        help form
        break down
        adhesion molecule
        binding and replication of influenza viruses
        recruitment of immune cells
        Changes in production
        Alzheimer’s early sign
        Globosides
        N-acetyl-galactosamine with 2 or more other carbohydrate molecules
        found in
        red blood cells
        serum
        liver
        spleen
        role in cell receptors
        Escherichia coli's binding
        in urinary tract infections
        Gangliosides
        with 1 or more sialic acid molecules
        often N-acetylneuraminic acid NANA
        Functions
        cell
        binding
        immune cells
        influenza virus
        cholera's toxin
        GM1
        recognition
        signaling
        abundant in nervous system
        Many types
        differ in
        carbohydrate & NANA molecules
        number
        location
Proteoglycans
- proteins that contain covalently linked
  - Glycosaminoglycans GAGs
    - unbranched polysaccharides
      - made up of repeating disaccharides
        amino sugar
        D-glucosamine
        D-galactosamine
        uronic acid
        except keratan sulfate
        all the GAGs contain sulfate groups
        except hyaluronic acid
        N-sulfate
        O-esters
        ones present in proteoglycans are polyanions
        bind polycations
        osmotic pressure
        seven GAG
        Keratan sulfate I & II
        Location
        Cartilage
        Eye
        Function
        Component of cartilage
        Cornea of the eye
        Hyaluronic acid
        Location
        synovial fluid
        bone
        cartilage
        vitreous humor
        embryonic tissues
        Skin
        Function
        Component of proteoglycan binding to collagen
        ECM in joints
        collagen binding in cornea
        Chondroitin sulfate
        Location
        Cartilage
        bone
        CNS
        Function
        Structural component and attachment point to collagen
        Dermatan sulfate
        Location
        Skin
        Eye
        circulatory system
        Function
        Structural component of skin
        collagen binding in cornea
        clot formation regulation
        Heparin
        Location
        Mast cells
        liver
        lung
        skin
        Regulates
        immune response
        blood clot formation
        Heparan sulfate
        Location
        Skin
        kidney
        collagen attachment
    - enzymes that degrade GAGs
      - endoglycosidases
        Deficiencies
        Mucopolysaccharidoses
      - exoglycosidases
        Deficiencies
- consists of
  - core protein bound covalently to GAGs
    - large complexes
      - bottlebrush structure
    - link proteins attach noncovalently
      - from which other GAGs project
- 30 have been characterized
- found in every tissue of the body
  - major component of extracellular matrix
    - associated with each other and other structural components of the matrix
      - collagen
      - elastin
      - bind growth factors
        TGF-β
      - adhesive proteins
        fibronectin
        laminin
    - sieves for macromolecules into the ECM

Bilder und Dateien der Mindmap

Informationen

Beschreibung: Medicina Mindmap am Glycoconjugates, erstellt von Valentina Ardila Mora am 12/10/2020.
Erstellt von: Valentina Ardila Mora
Aufrufe: 0
Bewertung

Glycoconjugates

Inhalt der Mindmap

Bilder und Dateien der Mindmap

Informationen

Feedback

Wie gefällt dir das neue Design?