MCPHS - MedChem I Exam b Flashcards

Terms Definitions
antagonists are?
up-regulated (super-sensitivity)
What does Penoxybenzamine block?
Allosteric Binding Antagonist Non-Competitive blocking ACh stopping skeletal muscle contraction
Agonists on nACh rcptr
rapidly developed tolerance is called?
angonists are ?
down regulated (desesitization)
receptor activity is regulated by?
Cimetidine ?
H2 Receptor Blocker (Competitive)
Where are targets located?
Extracellular, Cellular, Intracellular
what happens to receptors when morphine is administered for a long time?
Epi after Phentolamine ?
Drop in BP
Receptor Phosphorylation does what?
desensitization: Beta-adrenergic Rcptrs by B-ARK to Ser or Thr on C-terminal
how many time does Enzyme Linked Rcptrs Span the Membrane?
example: Extracellular?
Heparin & coagulation proteins, Ca/Mg Caronate & HCl (effect: decrease clotting or stomach acidity) *(Mech. of Action: Neutralization of co-agulation protiens or neutralization of Hydroprotic Acids)
What are Targets?
Enzymes, Carrier Molecules, Ion Channels, Receptors (The Nature of all these targets is that they are all proteins)
Four Types of Receptors?
Ligand-Gated (Chollnergic Nicotinic Rcptrs), G Protein-Coupled Rcptr (alpha & beta Adreno-Rcptrs), Enzyme-Linked Rcptrs (Insulin Rcptrs), Intracellular Rcptrs (Steroid Rcptrs)
How long does BARK Cycle take?
few min.s
Ez-Linked Tyr-Phosphatase?
Single, Signal mech (immune cells) Removes Phos.
Two types of antagonists?
Competitive (reversible) & Non-competitive (binds tight or on to allosteric site)
Bock same site as endogenous ligand, but No Intrinsic activity/efficacy.
What does activation of G-Pro Cpl'd Rcptrs produce?
2nd Messengers
What do Enzyme-Linked Rcptrs do?
Protein & Receptor Phosphorylation
example: Ion Chan?
Nifedipine on Ca chan.'s, General Anesthetics on K chan.'s
What does G 12/13 do?
Diverse Ion Transporter Interactions
Full Agonist?
Same efficacy but diff affinity (epi acts on alph1 incr. BP, Phenylephrine acts to produce equ. response )
reversible adaption?
can occur after a period of rest
What is CURL
Compartment of Uncoupling of Receptr and Ligand where receptor is recycleed while ligand *(agonist) is degraded
Partial Agonist?
Incr. Conc. does not produce Max Response even if max rcpts are occupied
What is Ser/Thr Kinases?
Dimerzied (two ligands) Ser/Thr Kinases (CA progression - TGF-Beta rcptrs & MAPK ) phosphoralates either ser or thr
What does Go do?
Inhibits Ca Chan's (Blocked by Pertussis Toxin)
example of Receptors?
ACh on Nicotanic & Muscarinic Rceptrs, or N.E. on alfa & beta Rcptrs
What are some functions of Ligand-Gated Ion Chan?
Neurotransmission, Cardiac Conduction, Skeletal Muscle Contraction
What are Ligand-Gated Ion Chan Rcptrs Also Called?
Channel Linked Receptors
What is an Irreversible antagonist?
Non-Competetive (binds to either allosteric or active site, but dissociation is slow to none)
Four types for Enzyme-linked ?
Tyrosine Kinase, Tyrosine Phosphatase (removes phos.), Ser/Thr Kinase, Guanylyl Cyclases (conv. GTP to cGMP)
Cross Talk?
%of types of rcptrs present on cell determine net effect
PSD - 95?
Post Synaptic Density Protein has PDZ domains that link to trans-membrane receptors (example of how rcptrs don't fxn' alone)
Intial therory of Drug-Receptor Interactions ?
Lock & Key Static Fit Model
example of Cellular Targets?
Ach on Ach Rcptr (effect: Contraction of muscle) Curar on ACh Rcptr (effect: Prevents Muscle Contraction)
What are Tyrosine & Phenylalenine responsible for in GABAa?
The AA responsible for binding
What kind of targets are there?
Specific (Quinine elim Plasmodium) reduced Fever, Non-Specific (Tylenol Re-Set Temp Reg Center, but no cure) lowers Fever only, Both = Tx's Sx & Cures Disease (Quinine also resets Temp Reg Center, so it does both)
Where may Receptors be present?
Cell Membranes (Dopamine, ACh Rcptrs), Cytoplasm (Glucocorticoid), Nucleus (Steroid Hormone Rcptrs)
How does BARK do this?
conformational change of tail on C-terminal that blocks cytosolic binding site of G-Protein
What is Heterologous desensitization?
sharing of effector that to receptor activations by different drugs cause both to be desensitzed
What is supersensitiveity?
Opp of Tolerance - Agonist causes a greater responce than normal
What does Imantinib do?
It is a cancer drug that Inhibits Phos.- Kinase by binding with AA residues with many weak vander wall and H-bonds Similar to the way enzyme-substrates interact
Where are agonist sites located on GABAa?
Between alfa & beta subunits
Who coined the term "Receptor"?
Paul Ehrlich (1909) Drug = 1st Messenger & Stimulated Effects inside a cell are caused by 2nd Messenger
What is the effect of Cl- moving in to CNS via GABAa?
Decreased Anxiety/Convulsions
What does cimetidine look like?
Histamine, so it blocks H2 receptor reducing acid secretion
What does Phosate addition do?
causes large neg charge added to protein. Changes 3D structure & activity. Teversible (reg in time & space)
What do Chan. Linked (Ligand-Gated Ion Chan.) Receptors do?
Cause changed in Ionic Membrane Potential
When ligand binds to ion chan rcptr what does it do?
Causes "Conformational" change in gate/pore by rotating the subunits
What are the G-Proteins made up of?
"HeteroTrimeric" = 3 subunits: alpha, beta, gama (one ea.) Alpha subunit binds to GDP, and Beta-Gama dislocate on outter membrane for other effects)
How do GABA a receptors interact with Benzodiazepines & Barbiturates?
Benzodiazepines & Barbiturates = Allosteric Modulation w/ GABAa
What happens when agonist is removed from desensitized receptor?
B-arrestin dissociates and phos. is removed from G-Protein and now a response can be activated again
How many Trans-Membrane (TM) domains can a subunit be made out of?
4 TM domains per subunit, where TM2 compose the inside gates of the ion channel
Can one Agonist have more than one effect?
yes, by binding with different types of Muscarinic receptors
Why is ACh a stimulator on ion gate?
opens gate causing Na+ to move in depolarizing neuron
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