Cell signalling Flashcards
What are the 4 routes that cells can receive signals
Endocrine: Very long distance and uses the bloodstream to reach cells in other parts of the body - slow.
Paracrine: signal secreted by cell and acts on local cells
Neuronal: Specialist paracrine signal, acts on one cell - single cell connection.
Contact dependant: Membrane bound signal molecule binds to a receptor on target cell - nothing is secreted.
Example of Endocrine, Paracrine and neurotransmitter signals
Endocrine: Hormones - testosterone, Oestradiol. Metabolic regulators- insulin, adrenaline
Paracrine growth factors - Epidermal Growth factor.
Neurotransmitter - Acetylcholine, Glutamate.
Example of signal molecules where the receptor is intracellular.
Steroid hormones - testosterone and oestradiol.
signal molecule needs to be small and hydrophobic
Where is the G protein interaction domain
Between 5th and 6th transmembrane regions.
Describe the G proteins in the active and inactive state
Inactive: form a trimer, not covalently bonded to each other. alpha is bound to GDP
Active: alpha subunit os bound to GTP and dissociated from beta and gamma. The activated alpha can catalyse the release of a phosphate group for GTP to become GDP and inactivated it.
Describe the stimulation of Adenylyl cyclase and PKA
adrenaline to the receptor which cause a change of conformation at the intracellular region. this allows it to bind to the G protein. The GDP bound to the alpha become GTP. the active alpha subunit actives adenylyl cyclase which changes ATP into cAMP(secondary messenger).
cAMP binds to the regulatory subunit of PKA which Releases the catalytic subunit which can phophorylate proteins causing altered protein structure causing altered cell behaviour.
