RECEPTORS

Memona
Mind Map by Memona, updated more than 1 year ago
Memona
Created by Memona over 6 years ago
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Description

An introduction to cell receptors How agonist and antagonist drugs interact with cell receptors How receptor proteins are classified An overview of the 4 main families of cell receptors

Resource summary

RECEPTORS
  1. Super Families of Receptor Proteins
    1. Plasma Membrane
      1. ligand gate ion channels
        1. eg nicotine and acetyl choline receptors
        2. G Protein coupled receptors
          1. aka signal proteins structure: 7 helices with N terminal on outside
            1. Binding site on inside usually closed, ligand binding causes conformational change to open this
              1. G protein (alpha beta & gamma) binds to inner bindng site
                1. Alpha usually has GDP (guanosine diphospate) which is then replaced GTP on activation
                  1. Gamma and beta separate
                    1. alpha inactivated when its own phosphoryating GTPase or protein phosphotase activity turn GDP to GTP
                      1. G protein subunits recombine and attach to cell membrane
                2. alpha activates adenylate cyclase to produce cyclic AMP
                  1. (secondary messenger) can go on to activate protein kinase A which activates phosphorylation of theorine and serine in other enzymes( glycogen to glucose)
                  2. DRUGS
                    1. Beta adrenergic receptors switched on by adrenaline
                      1. B1 open calcium channels
                        1. B2 close channels - asthma - relaxing smooth muscles
                        2. Muscuranic receptors -cholinergic receptors on smooth muscles and cardiac tissue
                          1. agonists switching on GI after surgery
                            1. antagonists close GI after surgery
                              1. shaking in parkisons
                          2. tyrosine kinase receptors
                            1. contain intra, extra & transcellular membrane
                            2. cytosolic intracellular
                              1. nucleur hormone receptors
                                1. involved in every major organ and metabolic system eg bone, muscle, hormone mediated cancer, homeostasis, sexual and embryonic development
                                  1. 2. binds receptor- conformational change
                                    1. 1. ligand crosses membrane
                                      1. 3. dimerisation
                                        1. 4. proteinsythesis
                                          1. 5. binds to coactivator protein
                                            1. 6. complex transloacates to nucleus and binds to specific region of DNA
                                              1. initiates transcription- directly involved in gene expression
                                              2. single protein steroid binding region near C terminal and DNA binding region near N terminal
                                                1. DNA binding region = zinc fingers 9 cysteine residues, 8 contain zinc to stabilise structure
                                                  1. dimer- both need to be activated- identifies particular nucleuotide sequence
                                                2. for steroids and thryroid
                                                  1. DRUGS
                                                    1. Glucocorticoid receptor: using adrenal gland extracts (cortisone) for allergy treatment. Abused by athletes.
                                                      1. Progesterone Receptor: control ovulation
                                                        1. Oestrogen receptor: using oestradiol for fertility control and breast cancers
                                                          1. oestrodiol = steroid effect growth and development
                                                            1. H12 folds across binding site which then exposes Activation Function AF2 (hydrophobic) after step two
                                                            2. Tamoxifen for breast cancer- prevents binding of oestrogen to its receptor
                                                      2. can be classified based on pharmacological activity (drug/ligand) nature here classified by structural pathway
                                                      3. Signal transduction process
                                                        1. Receptors = proteins receive endo/exodogenous signals
                                                          1. including hormones, neurotransmitters, local chemical mediators eg prostaglandins
                                                          2. Bind with high affinity, causing conformational change
                                                            1. Chemical signal transferred to intra cellular message
                                                            2. Drugs & Receptors
                                                              1. ANTAGONIST
                                                                1. competitive or non competitive
                                                                  1. binds to receptor but does not exert effect on cell
                                                                2. AGONIST
                                                                  1. partial or full
                                                                    1. exerts effect on cell
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