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Chemical signalling - Coggle Diagram
Chemical signalling
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Effectors
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Phospholipases
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A2
Cytosolic enzyme activated by calcium, hydrolyses membrane phospholipids into arachidonic acid which is a precursor for prostaglandin, thromboxane and leukotriene (inflammatory molecules) synthesis
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Kinases
Regulate proteins by phosphorylation of serine/threonine residues on protein, can switch them on/off
Relay signal from receptor to second messengers, usually by synthesising second messenger or activating it
Ligands
Protein hormones
Globular proteins (e.g. FSH, LH, GH)
Amine hormones
Modified amino acids (e.g. adrenaline, thyroxine)
Steroid hormones
Cholesterol derivatives (e.g. testosterone, oestrogen, progesterone, cortisol, aldosterone)
Receptors
Bind reversibly with ligands using weak bonds, ligand binding domain is usually complimentary to the ligand 3D shape
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Ionotropic receptors
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Ligand-gated ion channels which open upon ligand binding which permits passage of ions across membrane
Binding of ligand changes 3D configuration of channel, which in turn opens the pore
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Intracellular receptors
Examples: testosterone, oestrogen
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Second messengers
Calcium ions
Acts as a co-factor for many target proteins, exocytosis mediator, muscular contraction; regulated by calmodulin to activate CaM kinase
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IP3 and DAG
PIP2 hydrolysed by PLC into IP3 (soluble) and DAG (membrane bound). IP3 stimulates calcium release from SER, which triggers DAG translocation from membrane to activate protein kinase C
Termination of signals
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Reverse modifications to target proteins (e.g. protein phosphatases reversing the actions of protein kinases)
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