Term
| What type of receptor mediated cellular responses are the fastest? |
|
Definition
| Generally ionoptoric receptor mediated responses. |
|
|
Term
| What is the most studied g-protein-coupled-receptor? |
|
Definition
|
|
Term
| How are B2-adrenergic receptors inactivated? |
|
Definition
| By phosphorylation of serine and threonine residues in the third intracellular loop and the c-terminius. |
|
|
Term
| What subunit of a heterotrimeric g-protein is crucial for primary action? |
|
Definition
| The alpha subunit. Bacterial toxins target here. |
|
|
Term
| What to GTPase activating proteins (GAPs) do? |
|
Definition
| They help alpha subunits who don't have very good GTPase activity. |
|
|
Term
| How does amplification happen with GPCRs? |
|
Definition
| One GPCR can activate many g-proteins, and each alpha-GTP subunit can make a lot of second messenger molecule. |
|
|
Term
| What residues do protein kinases phosphorylate? |
|
Definition
| Serine or threonine residues |
|
|
Term
| What is conserved in many kinases? |
|
Definition
| The catalytic domain. The regulatory domains can be different. |
|
|
Term
| How are GPCRs uncoupled from g-protein activation? |
|
Definition
| A specific g-protein receptor kinase (GRK) gets phosphorylated or beta-arrestin binds to the third intracellular loop of the GPCR. |
|
|
Term
| What type of therapeutic interventions target GPCRs? |
|
Definition
| In Myasthenia gravis, antibodies block ACh receptor function. drugs can be use to inhibit acetylcholinesterase so that the synaptic concentration of ACh goes up. Remaining ACh receptors now have enough ACh to generate AP. |
|
|
Term
| What is the difference between Heterologous desensitization and Homologous desensitization? |
|
Definition
| Homologous desensitization only affects activated GPCRs. Heterologous desensitization affects both active AND inactive GPCRs (and steps in the signal cascade). |
|
|
Term
| What kind of mutation makes it hard for the alpha subunit to "turnoff" GTPase activity? |
|
Definition
| Missense mutations (to arginine 201 or glutamine 227). |
|
|
Term
| What type of mutations to GPCRs are recessive? |
|
Definition
| loss-of-function. Gain-of-function mutations are usually dominant. |
|
|
Term
| What is required for calmodulin activation? |
|
Definition
| Binding of 4 calcium ions. |
|
|
Term
| What removes the majority of calcium from the cytoplasm? |
|
Definition
| The sodium/calcium exchanger. These are found in the plasma membrane. |
|
|
