Cell Signaling Flashcards
Signals are produced by the target cell that stays within the target
Intracrine
Secondary messengers are _____ signals
Intracrine
Signals produced by the target cell that are secreted and affect target itself or nearby cell of same type via a receptor
Autocrine
Immune cells are ______ signals
Autocrine
Signals that target cells in the vicinity of the emitting cell
Paracrine
Neurotransmitters are _____ signals
Paracrine
Signals that target distance cells.
Endocrine
Cells that produce hormones that travel through bloodstream to reach all parts of body.
Endocrine
Hormones are _____ signals
Endocrine
Signals that target adjacent cells.
Juxtacrine
Signals that are transmitted along cell membranes via protein or lipid components integral to the membrane
Juxtacrine
Signals that are capable of affecting either the emitting cell or cells immediately adjacent
Juxtacrine
Gap (tight junctions, notch signaling) are _____ signals
Juxtacrine
3 types of cell surface receptors
- Ion channels/ionotrophic receptors
- Enzyme-linked receptors
- G-protein coupled receptors
Intracellular receptors
Nuclear hormone receptors
Ca++ is a _______ messenger
2nd
What is a molecule that is released in response to a first stimulus that triggers downstream cell responses often to a profound effect?
2nd messenger
How are cytosolic Ca++ levels kept low?
Ca++ ATPase pumps
What kind of channels are plasma membrane Ca++ channels?
Ligand gated or voltage gated channels
What kind of channels are ER Ca++ channels?
IP3 gated channels
2 ways increased Ca++ concentration activates effectors
- Directly
- Via Ca++ binding calmodulin
What causes genetic channelopathies?
Mutated genes that cause abnormal or absent channel proteins
What causes autoimmune and toxic channelopathies?
Antibodies or toxins that bind to channels
What causes transcriptional channelopathies?
Abnormal transcription of normal genes that causes aberrant expression of normal proteins
Which signal transducer protein goes with Tyrosine Kinase Receptor?
SH2 domain
What does Tyrosine Kinase Receptor bind with?
growth factor
What signal transducer protein goes with JAK-STAT Receptor?
STAT
What does JAK-STAT Receptor bind with?
cytokine
What signal transducer protein goes with Serine-Threonine Kinase Receptor?
Smad
What does Serine-Threonine Kinase Receptor bind with?
cytokine dimer
What facilitates enzymatic reactions that would not be favorable in the monomeric state to make it much more likely that they will phosphorylate each other due to their proximity?
dimerization or oligomerization
What causes transphosphorylation?
ligand-binding, dimerization
What do RTKs do?
Regulate:
Cell proliferation
Cell growth
Cell differentiation
Cell migration
Which receptors have a cysteine-rich domain?
- EGF receptor
- Insulin receptor (IGF-1 receptor)
- Eph receptor
Which receptors have an immunoglobulin-like domain?
- NGF receptor
- PDGF receptor
- M-CSF receptor
- FGF receptor
- VEGF receptor
- Eph receptor
Which receptor has a fibronectin type II-like domain?
Eph receptor
Which receptor has disulfide bonds?
Insulin receptor, IGF-1 receptor
Phosphatidylinositol is phosphorylated by kinases to make __________
PI 4,5-bisphosphate
What cleaves PI 4,5-bisphosphate to make DAG and IP3 second messengers?
phospholipase C
PI 3-kinases is phosphorylated by what?
PI 4,5-bisphosphate
What does phosphorylation of PI 3-kinase produce?
PI 3,4,5-triphosphate
What creates the docking site for proteins that contain pleckstrin homology (PH) domains?
PI 3,4,5-triphosphate
What is a good example of divergence in the pathway of signal transduction?
insulin receptor
What kind of processes does calmodulin mediate?
- Inflammation
- Metabolism
- Apoptosis
- Muscle contraction
- Intracellular movement
- Short-term memory
- Long-term memory
- Nerve growth
- Immune response
G-proteins store and transmit information based upon what?
their conformational state
Is the GDP-bound conformation of the G-protein active or inactive?
inactive
Is the GTP-bound conformation of the G-protein active or inactive?
active
Which G-protein conformation can bind downstream effectors?
GTP-bound conformation (active)
What speeds up activation (exchange of GDP for GTP) of G-proteins?
Guanine Nucleotide Exchange Factor enzymes (GEF)
What promotes inactivation of G-proteins?
GTPase-activator protein enzymes (GAP)
How does GAP enzymes inactive G-proteins?
speed up GTP hydrolysis
What are G-protein direct effectors?
- Ion channels
- PLC
- Adenylyl cyclase
- Phosphodiesterases
- GEFs (for Rho family GTPases)
There are more _______ than G-proteins or effectors.
GPCRs
Often a cell will only contain a few different _______.
GPCRs
Why is there only a few different GPCRs for olfactory?
If many odorant receptors were expressed, there would be no way to discriminate which one was active because they all couple to the same effectors
What is the basal state of heterotrimeric G-proteins?
Ga subunit:
- bound to GDP
- in complex with Gby subunits
Ligand binding to the GPCR causes what?
1- Activation of the GPCR
2- Conformational changes
3- Induces GEF activity
Which subunit does the GDP for GTP exchange occur?
Ga subunit
Where does the conformational change take place?
Ga subunit
What does the conformational change of the Ga subunit lead to?
Dissociation of the Ga subunit from:
- Receptor
- Gby subunit
What activates adenylyl cyclase?
heterotrimeric G-proteins
What enzyme degrades cAMP?
phosphodiesterase
What are most of the effects of cAMP mediated through?
- Protein kinase A (PKA)
- EPAC
What is EPAC?
GEF for Rap1 and Rap2
What happens when cAMP binds to the regulatory subunit of PKA?
dissociation of the catalytic subunit
What happens when cAMP binds to EPAC?
relieves auto inhibition of the GEF activity of the protein
In the GTP-bound form of Ras, which phosphate group on the bound nucleotide is involved in H-bonding?
gamma phosphate group
What does the gamma phosphate group H-bond to?
the main chain of atoms of conserved Threonine and Glycine residues
What happens when the gamma phosphate group H-bonds to T and G?
conformational rearrangements of the switch I and II regions of the protein
What are the steps of the Ras MAP Kinase pathway?
1- Growth factor binding and dimerization
2- Autophosphorylation
3- Binding of adaptor proteins such as Grb2
4- Complex assembly
5- Guanine nucleotide exchange and activation of Ras
6- Ras binds and initiates MAP kinase pathway
7- AP-1 (jun and fos) and transcription factor activated
8- Induction of myc and fos
9- Cell proliferation
Are ligands lipophobic or lipophilic molecules?
Lipophilic
What are some nuclear hormones?
- Steroid hormones
- Thyroid hormones
- Retinoids
Where do steroid hormones come from?
Cholesterol (sex hormones, vitamin D, cortisol)
Where do thyroid hormones come from?
tyrosine
Where do retinoids come from?
vitamin D
What are the steps of the lipophilic hormone pathway from the blood to the cell?
1- Hormone passes from the blood plasma through the plasma membrane
2- Hormone binds to a receptor protein in the cytoplasm or nucleus
3- Hormone-receptor complex binds to hormone response element on DNA regulating gene transcription
4- Protein synthesis
5- Change in protein synthesis is cellular response
What does glucagon release cause?
- Increased glycogenolysis
- Increased gluconeogenesis
- Increased lipolysis
- Decreased liver glycolysis
What does insulin release cause?
- Increased glycogen synthesis
- Increased FA synthesis
- Increased TAG synthesis
- Increased liver glycolysis