L3 Communication Between Cells Flashcards
Types of intercellular communication
- Autocrine: cell signals to itself
- Paracrine: cell signals to neighbouring cell
- Signalling via proteins attached to cell surface
- Synapic transmission: neurons
- Endocrine- endocrine cells release hormones to distant cells
Receptor def and function
Specialised protein
Receptor RECOGNISES signalling molecules
Binds to ligand
Trigger cellular responses-ACTION
When ligand binds the receptor changes shape
Can change function of cell
Activation of receptor can lead to
Means when Ligand and receptor attach :
- Changes in cell growth and division (mitosis)
- Change cell membrane permeability
Different classes of receptors
Intercellular - in nucleus or free floating in cytoplasm
OR
On cell surface
Note: receptors in cytoplasm do nothing
If ligand and intracellular receptor bind give an ex of a new function protein might gain as result
Permeability to cell membrane might increase
Intracellular receptors for signalling molecules which CAN pass through cell membrane
- Receptor & ligand bind
- Attach to DNA- results in activation of specific genes
- Results in activation of proteins
- These proteins can change cell function
- Note: only for LIGANds that can pass cell membrane
Eg of intercellular receptors
Steroid and thyroid hormone receptors
Where are receptors located for Ligand that can’t pass cell membrane
On cell surface
Second Messengers - what are they ?
When do receptors usually characterise SM
- Intracellular substance that can mediate cell activity by release or relaying of a signal of an extra cellular molecule bound to cell surface
- released by cell to cause a physiological change
- Receptors on cell membrane
E.g. ACh and adrenalin (hormone)
Cell charge for all? Ions:
Outside is +
Inside is -
Receptors found on cell membrane- list 3
- receptors which are ION CHANNELS
- receptors which are ENZYMES or bound to enzymes (protein KINASES cause phosphorylation)
- receptors which act as G-PROTEINS
Receptors which act as G protein
Activation process
Video NB
process from video
- Ligand binds to receptor that has alpha beta and gama subunits attached
- alpha has ADP attached also
- once Ligand binds sub units move away
- ATP now binds to alpha
- alpha moves away from beta and gama
- if Ligand is removed, alpha phosphorylates ; ADP binds back
- subunits return together to the receptor
Lecture notes
- They usually bind to other proteins changing their functions by binding to them (allosteric)
- May lead to activation of some enzymes to for e.g. Modulate ion channels - change MP.
E.g. Of receptor - ADRENALIN are receptor
Intracellular receptors bind to DNA and thus have a direct effect on : GENE EXPRESSION
- Have a direct effect in gene expression bcos they bind to - DNA
- Ligand & receptor
- DNA
- Genes
- Altered function
Receptors which act as G protein
Activation process
Video NB
-When activated, receptors make G-proteins separate into 2 subunits: alpha
Beta and gama
- They usually bind to other proteins changing their functions by binding to them (allosteric)
- May lead to activation of some enzymes to for e.g. Modulate ion channels - change MP.
E.g. Of receptor - ADRENALIN are receptor
Note what receptors use second and third intermediates to amplify initial signal
Receptors - enzymes and GCPR’s
