section 2 old Qs Flashcards
why is a receptor necessary for efficient signal transduction
d
ionotropic receptor vs ion channel
ionotropic receptor can be activated by a ligand binding, opening the receptor and allowing specific ions through
ion channnels just allow diffusion of ions down gradient
hydopathy plots
identify hydrophobicity of aa residues to see which is hydrophobic and membrane bounde to predict structure
generated by moving a window over residues, determining + values (lipophilc aa, hydrophobic), and - values (hydrophilic) graphe these, + peakes identify transmembrane domains
T/F all membrane associated proteins have N terminus on extracellular side
Flase
with certain receptors active, signaling intermediates dock to cytoplasmic face, what facilitates docking PTM? what is the purpose of docking?
d
2 ways to turn off receptors
Desensitization, sequestration
desensitization - phosphorylation of receptor subunits causes receptors to be unresponsive to further stimulation, Phosphorylation ovvurs via agonist binding which recuriots phosphorylaiton proteins and subsequite beta-arresting binding, can also be cross phosphoyryaltion or targetting by a second messenger like PKA
modifications of PI on the inositol head group
IP3 PI(3,4,5)P2 - PH domains PI(4)P PI(4,5)P2 PI(3,4)P2 PLC cleaves inositol head PI3 kinase
3 ways of activating phospholipase C
experiment to test mechanism
binding to the activated alpha sub unit following GPCR activation
binding to tbe Beta subunit following GPCR activation
Tyrosine Kinase activation forms a phosporylated binding site for PLC to dock
experiment: scratchard analysis of bound:free PLC in aprep with tryosine kinase receptor
in T cell anergy, DAG becomes what and what enzyme
phosphatidic acid
DGK
two functions of phosphoinositide lipids
docking site for PH domains
regulate ion channel activity
3 fates of arachidonic acid
Prostaglandins
Leukotrienes
PP5 activator
whats phosphorylation regulate
receptor desensitization
Cell structure and motility
advatage and disadvantage of kinase inhibitor to preven the binding of ATP to an enzyme
?
feature of tyrosine kinase
size of active site cleft - larger in a tyrosine kinase than a ser/thr kinase
structural feature that enables Cam kinase to remain active without calcium calmodulin bound
phosphorylated site (and substrate still bound to catalytic site) inactive once phoashpate cleaved by phosphorylase while bound to ca calmodulin
steps of JAK-STAT pathway after ligand and before transcription
phosphorylation of JAKS phosphorylation of receptor subunits recruitment of STATs phosphorylaiton of stats STAT dissociation STAT dimerization nuclear translocation of STATs
Catalysis by Ser/Thr phosphotases requireswhat metals
corresponding structural feature for Tyr phosphatases
zinc and iron for ser/thr
cysteine for tyr
events after stimulation of GPCRs by agonists before GPCR internalization
d
events after stimulation of GPCRs by agonists before g protein independent signaling
d
heterologous desensitization of GPCRs
receptor desensitized by another recepttor and its sginaling molecule cascades; one agonist can phosphorylate multiple types of receptors and the receptor phosphorylated isnt necessarilly what will be internalized like second messenger kinases
homologous desensitization of GPCRs
receptor desensitizes itself by signal molecule bound to it, receptor internalized is the same one thats phosphorylated like GPK
G alpha proteins
Gs
Gi
G protein effectors
adenylyl cyclace
Raf
G rpotein regulators
GAP
GEF
monmeric
Ras
Rho
regions of G
switch I and II domains within G odomain of G protein alpha subunit
swithc on: GPCR acts as GEF on G domain so conformational change allowing release of GDP and binding of GTP to activate alpha subunits
switch off: RGS ?? protein acts as a GAP to interact with switches to stabliize the transition state and allow more effficienct exchange GTP to GDP inactivates alpha subunit
