Receptors And Signal transduction Flashcards
What are the major modes of signaling?
- Direct Cell-cell (Gap junction)
- Membrane-bound molecules
- Receptor-mediated communication (surface receptors/nuclear receptors)
- Vesicular communication
- Inter-kingdom Comm
Define Agonist
A Ligand which causes the receptor to activate a response in the cell.
Define Antagonist
A ligand which causes the receptor to become inactive
Differentiate EC50 with Kd.
EC50 - [Drug] at which 50% of drug effect is observed
Kd - Dissociation constant at which 50% of drug is bound to receptor
What are the 3 main classifications of receptors?
- Ion channel-linked
- G-protein coupled
- Enzyme-linked
Differentiate Nicotinic and muscarinic receptors and their ligands in the PNS.
Nicotinic receptors are activate by sympathetic preganglionic Neurons which release Ach
Muscarinic receptors are activated by Ach in the parasympathetic nervous system by post-Ganglion is neurons
Which type of receptor is primarily involved in skeletal muscle contraction?
A. Parasympathetic Nicotinic
B. Somatic Nicotinic
C. sympathetic Muscarinic
D. Somatic Muscarinic
B. Somatic Nicotinic
What are two examples of Ach Nicotinic antagonist?
Cobra Toxin
Curare Plant
What are the three types of GPCRs?
GI, Gs, Gq
What are Beta-2 agonists used for?
Treatment of histamine-activated smooth muscle contraction (Asthma and allergies)
How can receptors become desensitized?
- Occurs via phosphorylation
- Ex. Phosphorylation Beta-2 receptors affect the regulation of histamine GPCRs through heterologous regulation —> synergistic affect towards vasodilation
Describe the pathway from receptor activation from insulin to uptake of glucose into the cell.
Insulin Binds -> Tyr Kinase autophosphorylates via ATP —> Mobilization of GLUT4 transporter to plasma membrane
What is a PAR?
a unique family of GPCRs that are irreversibly activated following proteolytic cleavage of their extracellular N-terminus.
What role do GPCRs play in the clotting cascade?
- Platelets express various GPCRs
- Activated platelets release coagulation factors which crease thrombin concentrations
- Thrombin activates PAR-1 on platelets and cleave amino terminals
- The remaining part is self-binding and activates intracellular events
What type of receptor is activated by thyroid hormone?
Nuclear receptor
What are the classifications of cell signals?
Endocrine - Ligand acts on far away signal
Paracrine - Ligand is secreted by one cella and acts on a nearby target
Autocrine - Ligand secreted acts on secreting cell and surrounding cells of the same type.
How are JAK-STAT receptors involved in immune response?
- Interferon receptors are JAK/STAT receptors
- Interferons such as IFN-gamma are important for stress response and inflammatory response
Differentiate Gq vs Gs responses in intracellular signal transduction.
Gq —> PLC —> PIP2 to IP3 + DAG —> IP3 opens Ca channels —> Ca + DAG bind PKC —>PKC phosphorylation and downstream affect
Gs —> Activate Adenylyl Cyclase —> Increase cAMP —> PKA —> Downstream affects
Which receptors acitvate Gq and smooth muscle contraction?
H1 (histamine)
Alpha-1 (Adrenergic)
V1 - (ADH)
M1/3 (Muscarinic)
“HAVe 1 M&M”
Which receptors are Gs and activate PKA resulting in increase Ca and inhibition of smooth muscle contraction?
Beta 1/2/3 Adrenergic
D1 (dopamine)
H2 (histamine)
V2 (ADH)
Which receptors are Gi and Inhibit Gs activity?
M2 (muscarinic)
Alpha 2 Adrenergic
D2 (Dopamine)
“MAD 2s”
Describe the pathology of Hyperhtyroidism and related diseases.
- Increase production of T#/T$
- T3 increase BMR
- Too much T# results in Tachcardia and Sympathetic response
- Weight loss, Heath intolerance, Sweating, Hyperactivity, anxiety, insomnia
- Graves’ disease, Goiter, and thyroid adenoma
