Physiology: Signal transduction Flashcards
A ligand/transmitter/chemical binds to its specific receptor and it will initiate a cascade of events that will ultimately result in the response that the specific cell should manifest
SIGNAL TRANSDUCTION
What type of signal transduction is Cholinergic nicotinic receptors under?
Ligand – gated ion channels
What type of signal transduction is α and β adrenoceptors under?
G protein - coupled receptors
What type of signal transduction is insulin receptors under?
Enzyme - linked receptors
What type of signal transduction is steroid receptors under?
Intracellular receptors
Receptor for caffeine in Ligand gated ion channel
Ryanodine receptor
What ion channel is opened by Ryanodine receptor?
calcium channel
They are opened or closed by hormones, second messengers, or neurotransmitters.
Ligand-gated channels
What enzyme does caffeine inhibit in G protein coupled receptor
Phosphodiesterase
opened or closed by changes in membrane potential.
Voltage-gated channels
mediate direct and rapid synaptic signaling between electrically excitable cells
Ligand-gated channels
regulate the activity of other proteins, such as enzymes and ion channels
GPCR
G protein sub units
α, β, and γ subunits
either function as enzymes or are associated with and regulate enzymes
Enzyme-linked receptors
T/F, Most enzyme-linked receptors are protein kinases or are associated with protein kinases,
True
small hydrophobic molecules, that have a long biological half-life (hours to days), diffuse across the plasma membrane, and bind to nuclear receptors or to cytoplasmic receptors that, once bound to their ligand, translocate to the nucleus
Nuclear receptors
Steroid hormones, thyroid hormones, retinoids, and vitamin D bind to what type of receptor
Nuclear receptors
This class of receptors transduces a chemical signal into an electrical signal, which elicits a response.
Ligand-gated channels
Activation of G protein stimulates ___ enzyme
Adenylate cyclase
Adenylate cyclase increases that level of___
cAMP
Increase level of cAMP activates what enzyme?
Protein Kinase A
Enzyme that breaks down cAMP
Phosphodiesterase enzymes
Phosphodiesterases facilitate the breakdown of cAMP and cGMP to
AMP and GMP,
Another way to degrade cAMP or cGMP is
dephosphorylation of effectors by protein phosphatases.
Effect of caffeine activation of cAMP and PKA
stimulate the release of calcium from the ER/SR Therefore, having more cardiac contraction and eventual palpitations.
promote the translocation of the glucose transporters from the cytoplasm to the cell membrane.
PI-3K pathway
glucose in the circulation can get into the cell by way of
glucose transporters.
General mechanism of Steroid when bound to DNA receptor
anti-inflammatory proteins are increased while pro-inflammatory proteins are inhibited
anti-inflammatory proteins that have been induced by steroid
Lipocortin-1 IL-10 IL1- receptor
inflammatory proteins are inhibited that have been inhibited by steroids
o ICAM-1 o IL-4 o IL- 5 o IL-6 o IL-13 o TNF- alpha o VCAM-1
released during penile erection and binds to its guanylyl cyclase receptor (similar to adenylyl cyclase) which will increases the formation of cGMP.
Nitric oxide
stimulate smooth (corpora cavernosa) muscle relaxation in penile erection
cGMP
an oral drug, inhibits phosphodiesterase enzyme.
Sildenafil (blue pill)
enzyme that releases arachidonic acid (AA)
Phospholipase A2
Three Pathways of A.A
Cyclooxygenase (COX) 5-Lipoxygenase Epoxygenase (Cytochrome P 450):
facilitates metabolism of AA to prostaglandin, thromboxane and prostacyclin
Cyclooxygenase (COX)
initiates conversion of AA to leukotrienes
5-Lipoxygenase
enzyme that facilitates generation of hydroxyeicosatetraenoic acid (HETE) and cis-epoxyeicosatrienoic acid (EET)
Epoxygenase (Cytochrome P 450):
mediate platelet aggregation, causes airway constriction, and induce inflammation
Prostaglandin
induces platelet aggregation, constrict blood vessels
Thromboxanes
inhibits platelet aggregation, dilates blood vessels
Prostacyclins
participates in allergic and inflammatory responses
Leukotrienes
increases release of Ca++ from ER and stimulate cell proliferation
HETE & EET
Explain the THE cAMP and Ca Pathway
Signal Molecule (e.g. epinephrine) binds to a cell surface receptor protein it activates a G protein inside of the cell. The G protein then stimulates adenylyl cyclase produce large amounts of cAMP within the cell. cAMP binds to and activates a target protein such as α-kinase which adds phosphates to specific proteins in the cell. The effect of this phosphorylation depends on the identity of the cell and the proteins that are phosphorylated Calcium Ions also serve as second messengers. In response to a signal molecule from other cells. The cell surface receptor proteins activates a G protein which in turn activates enzyme Phospholipase C. Phospholipase C catalyzes the production of Inositol triphosphate diffuses through the cytoplasm to the ER. The Inositol triphosphate binds to and opens Ca channels allowing Ca ions to flow from the ER into the cytoplasm. The Ca ions trigger protein sensitive to Ca to initiate a variety of activities.
catalyzes the production of Inositol
Phospholipase C
T/F, Steroid Hormone are not water soluble
true
DNA regions where steroid hormones bind
hormone response elements.
How does steroid works to reduce inflammation?
It binds to certain parts of the DNA which effect on the level of transcription of that site. The mRNA is produced which then codes for the synthesis of specific protein.
What is attached to the G protein subunit intracellularly prior to ligand binding
guanosine diphoshate(GDP)
What forms in the alpha subunit after ligand binding to G protein receptor
guanosine triphosphate(GTP)
photo receptors cells in the retina of the eye motor
Rod cells
photo receptor protein found in the outer segment of the rods are stacks of membranous disks and embedded in the disk membrane is called
Rhodopsin
light sensitive molecule found in the rhodopsin is called
retinal
Found in the outer membrane of the rod cGMP-gated
Na ion channels.
What happense when a photon of light strikes rhodopsin
retinal isomerization initiates rhodopsin activation
Active rhodopsin binds ___, a trimeric G protein.
transducin
aggressive breast cancer are driven by a transmembrane receptor protein known
HER2
How HER2 causes breast cancer
over expression is a trememdous increase in receptor mediated intracellular signaling
Ligands of Ligand gated ion channel
Ligand of GPCR
Ligands for Enzyme link receptor
Ligands for nuclear receptor
