Exam I Flashcards
What types of receptor proteins are there?
- Regulatory proteins
- Enzymatic proteins
- Transport proteins
- Structural proteins
What are orphan receptors?
Identified receptors with an unidentified endogenous ligand (approximately 500 unidentified).
What are the seven receptor targets for drugs?
- Seven-transmembrane (7TM) receptors (GPCRs)
- Ligand-gated channels
- Ion channels
- Catalytic receptors
- Nuclear receptors
- Transporters
- Enzymes
In Cell Signaling, what protein actually modifies cellular metabolism, function, movement, etc. ?
The Effector protein
Name the cell signaling components in order starting with the signaling molecule (i.e. drug, endogenous ligand, etc.)
1st - Signaling molecule, endogenous ligand
2nd - Receptor where ligand attaches
3rd - Signal transduction proteins and second messengers send signal.
4th - Effector protein receives signal and effects change.
Some drugs affect gene expression and in doing so have a lag period, why is this? how long is this typically?
- The lag period results from the process of transcription to translation to protein creation occurring.
- Responses seen 30 minutes to several hours.
Dose response to the coupling of a drug to a receptor can be _____ or _____. Explain the difference between the two.
- Linear or exponential.
1. In linear the number of receptors capture is directly related to effect, 25% receptors bound vs 50%.
2. In exponential, 1 receptor could send a signal cascade where 100’s or 1000’s of effector proteins are engaged for the one drug attached to the receptor.
What are kinase’s and what is their role in the cell signaling phosphorylation cascade?
Kinases are a phosphate group that binds to a signaling or secondary messenger protein and induces a cascade of messages reaching the effector proteins.
What are phosphatase’s and what is their role in the cell signaling phosphorylation cascade?
Phosphatases block phosphorylation cascade from continuing to occur by deleting a protein (or a phosphate group?) and blocking downstream effects.
What are the mechanisms for transmembrane signalling?
- Intracellular receptors (need to be lipid soluble)
- Cell Surface receptors (3)
- Ion channels - Catalytic - GPCRs
What are GPCRs? How many drugs are GPCRs?
- Guanine Triphosphide Protein Coupled Receptors (or just G-protein coupled receptors).
- 2/3rds of all non-antibiotics
- 500 identified, 500 orphan
What characterizes a “fast” GPCR response?
- metabotropic ion channels causing a flood of ions (ex. B1)
What characterizes a slow GPCR response?
Transcription factor activation
What are the secondary messengers in the GPCR response? Which two of these messengers come from the cell membrane?
- cAMP (cyclated ATP)
- cGMP
- Calcium
- DAG
- IP3
DAG and IP3 come from phospholipids in the cell membrane.
What are the primary ligands of Tyrosine Kinase Receptors (RTKs)?
- Growth factors
- Adhesions
The process for RTKs (Receptor Tyrosine Kinase) binding is essentially three steps, what are these steps?
- 2 ligands bind and produce dimer.
- Dimer now has activated tyrosine regions that get phosphorylated by ATP (6 phosphates).
- The phosphorylated tyrosine regions are “docked” by relay proteins (causing a conformational change in the proteins) and multiple downstream responses are activated.
Where are voltage gated channels found? What are their characteristics?
- Found in excitable cells
- Neurons, muscle, endocrine
- Closed at resting membrane potential
- Types based on what ion’s get through (Na+ vs K+ vs Ca2+)
What are the two types of Ligand-Gated Ion channels? What is the difference between these two?
- Ionotropic - Ligand binds on protein and the protein opens a channel on itself to let an ion through. (ACh receptors)
- Metabotropic - Ligand activates a GPCR that initiates a sequence to open an ion channel.
What types of ligands are able to reach intracellular receptors?
- Gasses (like NO, or CO2)
- Lipid soluble agents capable of passing through phospholipid bilayer.
Why do steroids take a while to effect a change?
Steroids must:
- Cross phospholipid bilayer.
- Attach to steroid receptor in cytoplasm.
- Bind to receptor site on chromatin
- Chromatin then activates mRNA transcription to create proteins.
Name 4 transmembrane signaling methods by which drug-receptor interactions exert their effects.
- Intracellular receptor (gasses. lipophillic molecules)
- ion channel
- Catalytic receptor
- GCPR
What does Drug Biotransformation refer to? Is drug biotransformation going to inactivate all drugs?
- Termination of drug activity w/ mechanisms aside from renal.
- .Metabolic conversion (as with prodrugs)
- Some metabolites become active after biotransformation.
- .Metabolic conversion (as with prodrugs)
Where does drug biotransformation primarily occur?
Liver
Describe the process of the liver biotransforming a PO ingested drug. Include anatomy and physiology of the process.
- GI tract
- Local GI venous system
- Hepatic portal vein
- Sinusoids
- Hepatic vein
- Vena Cava
- Systemic circulation.


