L1 - Molecular recognition, EPO

    Cards (19)

    • What are the features of cytokines?
      Small proteins - 5-20 kDa
      Released by and affect other cells
      Important for cells of the immune system
    • What is the role of cytokines?
      Cytokines produce the signals for receptors to pick up and recognise - eventually alters transcription
      Travel in the bloodstream
    • What are the 4 structural families?
      TNF - Tumour necrosis factor
      Interferons
      Chemokines
      Hematopoeitin
    • What is the structure of a Tumour necrosis factor (TNF)?
      Beta strand structure
      It is a ligand trimeric receptor
    • What is the structure of interferons?
      The cytokine is alpha helical
      The interferon receptors are beta stranded
    • What is the structure of chemokines?
      Small
      Beta-alpha fold - different folds cause different functions and structures
    • What is the structure and role of EPO hematopoeitin?
      Alpha helical structure
      The receptors are beta stranded - 2:1 ratio of receptors to EPO molecule
      The EPO molecule brings the receptors together - makes more blood cells
    • What does the cytokine response depend on?
      the expression of a cognate/associated receptor
      the cell type and development - chromatin structure, constellation of transcription factors (different receptors presented on cell surface) and developmental history
    • When is EPO produced?
      When the body needs more red blood cells for storing oxygen - eg in high altitudes
    • What is Hif?
      Hypoxia inducible factor - transcription factor
      Can detect low levels of oxygen - hypoxia
    • What is the role of Hif?
      In hypoxic conditions - asparagine hydroxylase hydroxylates asparagine amino acids on Hif1-alpha and stabilises it
      Hif1-alpha translocates to the nucleus and promotes EPO production.
      In normal oxygen level conditions - prolyl hydroxylase hydroxylates proline amino acids on Hif1-alpha
      Marks it for ubiquitylation and destruction - no EPO production
    • What does EPO stand for?
      Erythropoietin
    • What does EPO do?
      EPO is a cytokine and stimulates red blood cell maturation
      EPO activates erythroid progenitor cells - produces erythroids (red blood cells)
    • What are CFU-Es?
      Colony Forming Unit - Erythroid
      EPO binds to EPO receptors on erythroid progenitor cells - it then divides and forms more cells
      EPO acts as a signal
    • What happens if there is no EPO binding to the erythroid progenitor cell?
      Apoptosis - cell death
    • What happens to the number of receptors on the cell surface as EPO cells divide and mature?
      The number of receptors reduce until the cells have fully matured into red blood cells - no receptors left on the cell surface
    • What is Kd?
      The disassociation constant
    • How many EPO receptors does an erythroid progenitor cell have?
      1000 EPO receptors - only 100 need to be occupied to elicit a cellular response (division)
    • What can the use of EPO help to treat?
      Anemia in some conditions - eg chronic kidney disease and Crohn's disease
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