4, 9/8 Ligands and drug targets

Exam 1, Lecture 21

What are the different types of receptors

ligand gated ion channels, g coupled, tyrosine kinase, nuclear receptors

WHat is the weakest form of drug binding

Van der Waals

What is the strongest form of drug binding

covalent

what are ionotropic receptors

agonist regulated, acts on selective ion channels

What are metabotropic receptors

affect metabolic processess within the cell

What type of agonists need receptors

Large, hydrophilic

What opens a ligan gated ion channel

When the agonist binds to the receptor

What is the purpose of a ligand gated ion channel

regulate the flow of ions through the cellular membrane

how long does the response take in an ion gated ligand channel

seconds

What kind of drugs use ligand gated ion channels

Anesthetics, benzos

how is the signal transduced in g protein coupled receptors

Through the G proteins

What types of channels are activated by g protein coupled receptors

Ca, K channels

WHat is the second messenger for Gas

cAMP

What does Gas stimulate

adenylyl cyclase

what does adenylyl cyclase do after being stimulated by gas

Changes ATP into cyclic AMP

What does cyclic amp do in the gas pathway

Binds to PKA and activates it

WHat does PKA do in the Gas pathway

phosphorylates proteins on the cell membrane to open channels

What does Gaq stimulate

Phospholipase C

What does phospholipase C activate in the Gas pathway

PIP2

What does PIP2 stimulate in the gas pathway

DAG and IP3

What does DAG do in the daq pathway

activates protien kinace C

What does IP3 do in the daq pathway

creates calcium

What drug uses tyrosine kinase

insulin

How deos tyrosine kinase transmit its signal

By changing its shape

What is added to tyrosine kinase to make it activated

Phosphorylation to the tyrosine subunits

What kind of drugs can use intracellualr receptors

highly lipid soluble and can cross cell membrane

What is the response time of intracellular receptors

minutes to hours

What does the receptor drug complex do in intracellular receptors

increases binding of RNA polymerase to transcribe genes

What are some examples of secondary messengers

Ca, nitric oxide, cAMP, cGMP

Where is cGMP a secondary messenger

plasma membrane

What is the purpose of secondary messengers

relay signals from receptors to target molecules, amplify the strength of the signal

What is upregulation

having more receptors

What is down regulation

having less receptors

Why does upregulation occur

Long term administration of antagonist, prolonged blockage of the receptors

What is upregulation also called

Supersensitivity

What is downregulation also called

desensitization

What causes down regulation

long term exposure to agonists

What is efficacy

the drugs ability, once bound, to produce a response

How is efficacy measured

Emax

What is potency

The concentration of a drug needed to achieve therapeutic effects

How are EC50 and potency related

Inversely

How is potency measured

EC50

When is potency the limiting factor on drug administration

drugs with small doses

What is a selective drug

Drug only produces a single effect

what is an example of a selective drug

Heparin for anticoagulant

what is a specific drug

Drug that only acts on one receptor, but can produce many effects

What is an example of a specific drug

atropine

What is a non specific drug

one with several mechanisms of action

What is an example of a non specific drug

acepromazine; sedation, hypotension, hypothermia

What is specificity linked to

macromolecule structure of receptors and 3D structure of binding ligands