Bartling SG Flashcards
Cells detect, amplify, and integrate external signals by way of
transduction cassettes
Specific cell surface membrane receptors, Effector signaling elements, Regulatory proteins are components of
transduction cassettes
What happens when a ligand binds to a specific receptor protein on the cell surface
Change in confirmation
Change in cellular metabolism, function, or development is
cellular response
What happens after the cellular response has been activated what happens to the ligand
Ligand is removed
After the ligand is removed what happens
Ligand is degrated
What is the first step in cell signaling
synthesis of ligand
Signaling molecule
ligand
What are chemical messengers
Hormones
What types of cells makes chemical messengers (hormones)
Endocrine cells
Gene expression and protein synthesis are affect by
Chemical messengers
Chemical messengers that act on same cell that secreted them
Autocrine
Chemical messengers that act on other cells
Paracrine
Types of hormones chemical messengers
Steroids
Amine
Peptide
Polypeptide
Amino acid-derived chemical messenger
Amine
Corticosteroids, Androgens, Estrogens are
Cholesterol precursor
Chemical messengers that can cross the cell membrane are
lipid soluble
Steroid hormone messengers are
lipid soluble
Intracellular (cytoplasmic) receptors for this type of chemical messenger are located inside target
Steroid hormones
How do steroid hormones reach there target
Through the blood stream
How are steroid hormones are released from the cell that synthesizes them
Immediately diffuse out
Steroid hormones are synthesized and released by
endocrine cells
- Synthesis of the signaling molecule (ligand)
- Release of the signaling molecule (ligand)
- Transport of signaling molecule to target cell
- Binding of the ligand by a specific receptor protein and change in conformation
- Change in cellular metabolism, function, or development = cellular response
- Removal of ligand, terminating cellular response
- Degradation of ligand
Know these 6 steps
If a chemical signal is slow acting it has a
Longer half-life
Steroid hormones has a longer half-life than
peptide hormones
Amine hormones are derived from
Tyrosine or tryptophan
How are amine hormones are released from the cell that synthesizes them
Stored until needed
What types of cells produce amino hormones
Endocrine
Where are the receptors for amine hormones located on target cells
Cell surface or intracellular
Hormones that are not imitate;y released into the blood stream
Polypeptide
Amine
Type of hormone that is water soluble
Polypeptide
Polypeptide are considered to be
First messengers
Polypeptide are first messengers because they bind to
External receptors
Intracellular effects of a polypeptide hormones are mediated by
Second messenger
A second messenger example is
cAMP
Second messenger molecules are
Low molecular-weight
Another second messenger example is
Calcium
Do polypeptide hormone pass immediately into the target cell?
No
Polypeptide hormones activate their target cells by way of
second messagers
What converts ATP to cAMP
adenylyl cyclase
Adenylyl cyclase is activated by what part of the G-protein
α-subunit
What activates Adenylyl cyclase
G-Protein
What inactivates / turns off cAMP
Phosphodiesterase
What does cAMP activate
Protein kinase
Where is the cAMP activated protein kinase located
Cytosol
What does G-protein do to the cell signal
Amplifies
What do the bacterial toxins target
G-protein
ADP-ribosylates Gs α-subunit
Cholera toxin
What does cholera toxin do to cAMP
increases
What cell does the cholera toxin target
intestinal G-protein
An increase cAMP within intestinal epithelial cells leads to
phosphorylation of Cl
Cholera toxin leads to
efflux of electrolytes and water
Whooping cough is caused by
Pertussis toxin
Pertussis toxin does what to cAMP
enhances
An enhance of pertussis toxin does what to neutrophils
inhibits functions
Pertussis toxin effects
neutrophils
Ligand binding forms dimer that activates
tyrosine kinases
Tyrosine kinases does what to downstream targets
phosphorylates
Does tyrosine kinases have intrinsic enzymatic activity
No
when phosphorylation of tyrosine kinase occurs it activates
other protein kinases
When ligand binding occurs to an ion channel what happen s
confirmation change
Ligand binding changes confirmation of ion channel receptor
Ions flow through
What type of ions flow through ion channels
Na and K
Bacterial toxin that indirectly affects ion-channels
Botulinum
Prevents release of acetylcholine neurotransmitter and cleaves proteins involved in docking of neurotransmitter vesicles
Botulinum toxin
What does Botulinum prevent the release of?
acetylcholine
What is acetylcholine
neurotransmitter
Calcium binds to what protein inducing conformational change
calmodulin
When calcium binds to calmodulin what happens
Conformational change
What conformational change occurs in the Calcium and calmodulin binding
Two globular domains joined
What join the two globular domains
a long α-helix
Calcium/calmodulin complex binds to and modifies
protein kinase
Calcium/calmodulin complex activates
signal cascade
Second messenger responsible for calcium mobilization
PIP2
Phosphatidylinositol 4,5-bisphosphate
PIP2
What is PIP2 hydrolyzed by
(PLC)
PIP2-specific phospholipase C
What PLC generate
Two second messengers
What are the two second messengers of PLC
Inositol trisphosphate (IP3) Diacylglycerol (DAG)
Second messenger that is water soluble and mobilizes calcium
Inositol trisphosphate (IP3)
Second messenger that is anchored in plasma membrane due to hydrophobic fatty acid side chains
Diacylglycerol (DAG)
Second messenger that activates key protein kinase C (PKC) family
Diacylglycerol (DAG)
Can be hydrolyzed by other phospholipases to produce other lipid second messengers
Phosphatidylcholine
Different species of DAG (generated by PLC), Phosphatidic acid (generated by PLD) and Arachidonic acid (generated by PLA2) are
Lipid second messengers
Key inflammatory and pain mediator
Arachidonic acid and prostaglandins
Prostaglandins, prostacyclins, thromboxanes, and leukotrienes are precursors of
eicosanoids
Act like hormones and signal via G-protein coupled receptors
Prostaglandins
Modulate smooth muscle contraction, platelet aggregation, gastric acid secretion, and salt and water balance
Arachidonic acid and prostaglandins
Arachidonic acid conversion to prostaglandins involves
cyclooxygenase isoforms
Nonsteroidal anti-inflammatory drugs (NSAIDs)
Aspirin and Ibuprofen
Response to inflammatory mediators
COX-2
cyclooxygenase isoforms
COX-1 and COX-2
Modulate smooth muscle contraction, platelet aggregation, gastric acid secretion, and salt and water balance
Arachidonic acid and prostaglandins
Anti-inflammatory drugs block cyclooxygenase conversion to
prostaglandins
Nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit
cyclooxygenase
What irreversibly inactivates both forms cyclooxygenase
Aspirin
selective inhibitions of what effective treatments for inflammatory conditions (rheumatoid arthritis)
COX-2 (celecoxib)
Selective inhibitors of COX-2 (celecoxib) are effective treatments for
inflammatory conditions (rheumatoid arthritis)
Arachidonic acid can also be converted into what by lipoxygenases
leukotrienes