types of receptors

what is a tyrosine kinase receptor

protein on surface of cells that helps cell respond to signals from outside the body

what types of signals does a tyrosine kinase receptor respond to

growth factors

hormones

insulin

how does a tyrosine kinase receptor work? (step by step)

1. signal binds to receptor

2. receptor join together (dimeristaion)

3. activation by phosphorylation

4. sends the message inside

what type of molecule binds to the outside of tyrosine kinase receptor

insulin or (EGF) epidermal growth factor

what haapnes once the signal binds in tyrosine kinase receptor

2 receptor proteins come together

what occurs in autophosphorylation

inside the cell adds phosphate groups to tyrosine molecules (amino acids) on the receptor itself

what is the role of the phsophate groups in tyrosine kinase receptor

act like ‘on switches’ that attract other proteins

carry signal deeper into cell & trigger response (activate genes & making proteins)

what type of processes does tyrosine kinase receptor help control

cell growth

healing

regualting blood sugar

what are nuclear receptors?

transcription factors

what is the role of nuclear receptors?

proetins that help turn specific genes on or off by binding to DNA

what are nuclear receptors directly activated by?

small, hydrophobic molecules

like steriod hormones

Examples of steroid hormones

estrogen

testosterone

thyroid hormones

vitamins A & B

what do nuclear receptors do? (step by step)

1. regulate gene expression

2. respond to hormone & signals

3. maintain physiological balance

what do nuclear receptors control?

transcription of target genes, affecting cell development, metabolism & homeostatsis

what do nuclear receptors senses the presence of?

certain molecules (hormones) & change gene expression in response

what processes are nuclear receptors involved in?

metabolsim (PPARs)

reproductive functions (estrogen & androgen receptors)

immune responses & inflammation (glucocortoid receptor)

how do nuclear receptors work?

1. ligand binding

2. conformational change

3. dimerisation

4. nuclear transolcation

5. DNA binding

6. recruitment of coregulators

7. gene transcription modulation

what is an example of a lipophilic ligand & what does it do?

cortisol, estrogen

diffuses across the cell membrane & binds to nuclear receptor

how is a nuclear receptor activated

when a ligand binds and changes the recptor shape

what does the activated nuclear receptor bind to?

specific DNA sequences (hormone response elements HREs) in the promoter region of target genes

what is a endogenous ligand

naturally produced by the body

what is the funstion of a endogenous ligand

bind to receptors to regulate normal physiological processes

examples of endogenous ligands

hormones (like cortisol binds to glucocortoid receptors)

neurotransmitters (like dopamine or serotonin)

thyroid hormone (bind to thyroid hormone receptors)

what are exogenous ligands

ligands that come from outside the body

what is the function of exogneous ligands

mimic, block or alter the action of endogenous ligands

examples of exogenous ligands

drugs (tamoxifen binds to estrogen receptors) (morphine binds to opoid receptors)

environmental chemicals (endocrine disruptors like bisphenol A)

toxins (nicotine binds to acetylcholine receptors)

what are G-Protein-coupled receptors

cell surface receptors that detect molecules outside the cell

trigger internal signal transduction pathways

what do G-Protein-coupled receptors once activated by ligands?

interact with G-proteins inside the cell

activate downstream effect

how do G-Protein-coupled receptors work?

1. ligand binding

2. conformational change

3. G-protein activation

4. subunit dissociation

5. signal propagtion

6. signal termination

what binds to the extracellular domain of G-Protein-coupled receptors

agoinst adrenaline

what are ligand-gated ion channels?

membrane proteins that allow ions to pass through cell membrane only when specific ligand (neurotransmitters) bind to them

what do ligand gated ion channels do?

convert a chemical signal into an electrical signal

regular rapid cell to cell communication

how do ligand gated ion channels work

1. resting state

2. ligand binding

3. conformational change

4. change in membrane potential

5. ligand removal & channel closure

what occurs in the resting state of a ligand gated ion channels?

channel is closed

no ions flow across memebrane

examples of ligands that bind to ligand gated ion channels?

acetylcholine

GABA

glutamate

What ions do ligand-gated ion channels allow to flow down their electrochemical gradient?

Na+

K+

CA(2+)

Cl-

what does the flow of ions down a ligand gated ion channel lead to?

depolarisation of cell membarne

trigger/inhibit an action potential

how is a ligand gated ion channel closed?

once ligand detaches or is broken down