The flashcards below were created by user
xijunzhu
on FreezingBlue Flashcards.
-
what are the stages of autophagy?
- envelopment
- sealing
- merging with lysosome
- resulting residual body
-
what is the function of ESCRT?
bring receptors together to concentrate them and then MVB's fuse with lysosome to rid receptors (reuse them)
-
how does cell downregulate signal?
by bringing it in and sending them to degradation pathway
-
how does the secretory system work?
- cargo proteins are translocated to the ER lumen
- in the ER, cargo fold and inserted into VTCs
- VTCs transport cargo to Golgi, where their oligosaccharide and polypeptide chains are processed
- motors are translocated
-
what's the signal for proteosome?
multiple ubiquitin attached
-
how does ubiquitin attach to E1?
using ATP
-
describe the process of ubiquitin conjugation mechanism
- using ATP, ubiquitin attached to E1, ubiquitin-acitivating enzyme
- E2 attaches to ubiquitin and recognizes protein for degradation,
- coupled to E3 (protein ligase) binds to prtein to be degraded, and transfers ubiquitin from E2 to protein using ATP
- proteosome chews protein up into aa and small peptides to be recycled
-
how do cells respond to their environment?
each cell expresses a genetically programmed repertoire of receptors, transuction hardware and effector system
-
how does signal transduction affect cells?
change in gene expression, cell shape, cell movement, cell metabolism
-
why do most stimuli react on receptors at PM?
they cannot penetrate PM, some light, steroid hormones, gases can penetrate PM,
-
how are receptors inactivated?
negative feedback, inhibitory ligand binding and phosphorylation of receptor
-
what are the two classes of signaling molecules?
- large requiring cell surface receptors (growth factors, cell cell interactions)
- small or hydrophobic and able to cross PM
-
signals lead to both short term and long term effect; what are the short and long term effects?
- short term: change in cell activity in cytoplasm (altering protein function)
- long term: altering gene expression (can be affected by the same signaling molecule)
-
what is the general pathway of cell receptors?
- signal transduction (converts mechanical or chemical mechanism to specific cellular response)
- amplification
- feedback loops
-
what is the effector of seven-helix?
trimeric G protein
-
what is the effector of receptor tyrosine kinase and cytokine?
tyrosine phosphorylation
-
what is the effector of receptro guanylyl cyclase?
cGMP
-
how does receptors transfer signal?
by conformational change or clustering to activate each other
-
what are the three major classes of cell surface receptors?
- ion channel linked receptors
- G-protein linked receptors
- enzyme linked receptors
-
what are the characteristics of seven helix receptor?
- use trimeric G-proteins to relay signal
- largest family of receptors; very ancient
- drug targets
- structurally similar to rhodopsin
- olfactory neurons and sight associated with this kind of receptors
-
where does rod photoreceptors process light signals?
in their outer segments
-
how is rhodopsin activated?
light binding to retinal will activate transducin, a heterotrimeric G protein
-
what promotes the exchange of GTP for GDP, activating the G protein?
ligand binding
-
what is the role of alpha and gamma subunits of trimeric g protein?
- alpha and gamma both have tails anchored on PM, alpha is regulated by GAP and GEF (activate and inactivate it)
- alpha and beta subunits are activated by GTP binding
-
how is the G protein coupled receptors activated?
- ligand binds to receptor (changes in conformation)
- G-protein binds to G protein coupled receptor, which exchange GTP for GDP (subunits separate)
-
what activates ATP bound protein?
- ATP (protein kinase turns it on)
- protein phosphatase dephosphorylates turns it off
-
how to activate and inactivate signaling by GTP binding?
GTP bound is on, GTP hydrolysis is off
-
what are the molecular switches that activate and inactivate monomeric proteins?
- GAPs induces hydrolysis of GTP (inactivating)
- GEFs are activating
-
describe signaling amplification in the retina
- one rhodopsin molecule absorbs one photon
- G protein (transducin) activated
- cyclic GMP phosphodiesterase activated
- Na channels close (change in membrane potential
- signal to brain
-
what terminates G protein activation and causes reassociation of trimer?
GTPase of alpha subunit
-
what are the different receptor signaling types?
- endocrine (through blood stream)
- paracrine (close contact with another cell)
- contact dependent (regulating self)
- snaptic (neuronal )
-
what are the signaling molecules?
- ligands (change shape and activity)
- small molecules (lipophilic-intracellular receptors in cytosol or nucleus which bind to transcription factors)
-
can steroid hormones cross membranes?
yes, binds directly to nuclear receptors, influencing transcription, all made from cholesterol
-
what are the different types of steroid hormones?
- cortisol
- estradiol
- testosterone
- thyroxine
-
what are the different growth factor receptors?
- receptor tyrosine kinases
- cytokine receptors
- receptor serine/threonine kinases
-
what does ligand binding do in receptor tyrosine kinases?
induces dimerization and activation
-
EGF binding does what to an autoinhibited monomer?
ligand binding opens extracellular domains
-
what is a SH2 protein?
- Grb2 is an example
- bind to P-tyr motif in receptor, which binds other proteins
-
what is the role of Ras (G protein)
- activates MAP kinase cascade
- GDPases as molecular switches
- RasGAP hydrolyze GTP to GDP
- only active when linked to PM
|
|