2.10 Signal Transduction and Second Messengers Flashcards
Conversion of one form of information to another
Usually a biochemical response
Signal transduction
Multiplication of an original signal
Signal amplication
The signal is meant for specific recipient
Target specificity/selectivity
How cells receive, process, and respond to external information
Information metabolism
Pathways that mediate the sensing and processing of stimuli
Signal-transduction cascasdes
Modes of signaling
Passed into blood for reception in target cells that are distant from the site of creation
Endocrine
Modes of signaling
Passed into nearby cellular spaces for action on cells in close proximity to the site of creation
Paracrine
Modes of signaling
Transmitted via synapses
For propagation of neural impulses
Neuronal
Modes of signaling
Juxtacrine interactions
Bound to the plasma membrane of the signaling cells to interact with a receptor on a directly adjacent cell
Contact-dependent signaling
Communication of cells is provided by ____ and ____.
Cell signaling
Transduction
5 phases of signal transduction
Signal Reception Integration/Adaptation Amplification Target
Transmit a signal when bound to GTP and are silent when bound to GDP
G proteins
Extracellular signaling molecules fall into 2 classes
Cell-surface receptors
Intracellular receptors
Intracellular molecules that change in concentration in response to environmental signals
Second messengers
Receptors for nitric oxide (NO)
Soluble Guanylyl Cyclases
Reactive free-radical that acts either as a neurotransmitter or as a second messenger
Nitric oxide
Two types of receptors that are possible for steroid hormones
Intracellular receptors
Membrane bound receptors
Can translocate to the nucleus and direct gene expression
May take hours or days
Intracellular receptors
Can act on the cellular players with immediate action
Membrane bound receptors
The steroid intracellular receptor superfamily are ____
Transcription factors
Phases of signal transduction
Signal Reception Integration/Adaption (Second messenger) Amplification (Second messenger) Target
In membrane receptor-mediated signal transduction, ____ is a common means of information transfer
Protein phosphorylation
Small hydrophobic signal molecules diffuse directly across the lipid bilayer therefore they bind to intracellular receptors
Intracellular-Receptor-Mediated Signals
True or False
Many receptors are kinases or are associated with kinases. Cytokine receptor superfamily is similar to the receptor-tyrosine-kinases and has the same receptors and kinases.
False
Cytokine receptor superfamily has separate receptors and kinases to the receptor-tyrosine-kinases
Tyrosine kinases may activate one form of ____, PLC-gamma
Phospholipase C
Receptors that usually interact with polar hydrophilic signaling molecules for receiving environmental signals
Cell surface receptors
Receptors that interact with nonpolar, hydrophobic signaling molecules, usually for fine tuning signaling within a cell
Intracellular receptors
What classification do non-steroid hormones fall under? Why?
Cell surface receptors
Polar and hydrophilic
One or more components of one signal transduction pathway affects the another
Cross talk
Phases of signal transduction
Signal Reception Integration/Adaption (Second messenger) Amplification (Second messenger) Target
Reactive free radical that relaxes vascular smooth muscles and stimulates macrophages to kill tumor cells and bacteria
Nitric Oxide
Small hyprophobic signal molecules diffuse directly across the lipid bilayer therefore they bind to intracellular receptors
Intracellular-Receptor-Mediated Signals
The hydrolysis of Phosphatidylinositol bisphosphate by phospholipase C generates how many messengers?
2
Calmodulin is activated by the binding of __ ions, when the cytosolic calcium level is raised above 500 nM
Calcium
Inositol 1,4,5-triphosphate opens channels to release __ ions from intracellular stores
calcium
Two messengers generated by the hydrolysis of phosphatidylinositol bisphosphate
Diacylglycerol
Inositol 1,4,5-triphosphate
On hydrolysis of the bound GTP by the intrinsic GTPase activity of Ga, Ga reassociates with the bg subunits to form the heterotrimeric G protein, thereby terminating the activation of ___.
Adenyl cyclase
Activates PKC
Diacylglycerol
True or False
DAG and IP3 work in tandem
True
A 17-kD protein with four calcium-binding sites and a member of the EF-hand protein family
Calmodulin
cAMP is degraded by ___
cAMP phosphodiesterase
Epinephrine targets a ___ coupled receptor
G-protein
True or False
The role of the hormone-bound receptor is to inhibit the exchange of GTP for bound GDP
False
It functions to catalyze, not to inhibit
On hydrolysis of the bound GTP by the intrinsic GTPase activity of Ga, Ga reassociates with the bg subunits to form the heterotrimeric G protein, thereby terminating the activation of ___.
Adenyl cyclase
Some G proteins regulate membrane bound enzymes to make ___.
Second messengers
Converts ATP into cAMP
Adenylyl cyclase
Name the 2 separate insulin signaling cascades lead to GLUT4 translocation to the the plasma membrane.
TC10
PPIn-3 kinase
cAMP is degraded by ___
cAMP phosphodiesterase
Forms of Cell surface receptors
Ion channel linked
Enzyme linked
Gprotein
Cell surface receptors that are regulated by signaling molecules.
Channels are often in neurons and muscles
Ion channel linked receptors
Cell surface receptors wherein binding of molecule to receptor either activates the catalytic domain of the receptor or alters the receptor such that it associates with an active cytoplasmic enzyme
Enzyme linked receptors
Cell surface receptors that activate g proteins that activate the enzyme or opens the ion channel
G protein receptors
General mechanism for Membrane-Receptor Mediated Signals
1) Membrane receptors transfer info from the environment to the cell’s interior
2) Second Messengers relay information from the receptor ligand complex
3) Protein phosphorylation (probably, it’s common)
4) Termination of signal
One or more components of one signal transduction pathway affects the another
Cross talk
cAMP activates ___
cAMP-dependent protein kinase (PKA)
Phosphorylation of cellular proteins by PKA causes the cellular response to ___
Epinephrine
True or False
PKA can phosphorylate enzymes and transcriptional activators
True
True or False
Glycogen metabolism is regulated by dephosphorylation of glycogen synthase and glycogen phosphorylase
False
PKA can phosphorylate __ channels to close them, which increases the excitability of the target cell.
Potassium
Name the 2 separate insulin signaling cascades that lead to GLUT4 translocation to the plasma membrane.
TC10
PPIn-3 kinase
Cholera and whooping cough are due to altered __ activity.
G-protein
Cholera: (activates/inactivates) G-protein
Activates
Pertussis or whooping cough: (activates/inactivates) G-protein
Inactivates
In chronic myelogenous leukemia, bcr-abl gene is expressed at (lower/higher) levels.
Higher
___ is involved in Alzheimer’s disease
Abl kinase