Membrane Bound Proteins Flashcards
(20 cards)
what do kinases (phosphotransferases) catalyse?
reversible phosphorylation of specific serine, threonine, tyrosine, histidine
what are kinases a key target for?
new anti-cancer drugs
what are the different types of integral membrane proteins?
I - VI
what do type I and II differ in?
domain orientation
what does type IV involve?
multiple PPC
what do types V and VI have?
covalent lipid anchors
how many turns do most transmembrane helices have?
6-7
in the erythrocyte glycoprotein, what does each hexagon represent?
tetrasaccharide
what does the hydropathy index tell you?
how hydrophobic AA is
neg number = hydrophilic
positive hydropathy windows for 20 residues in a row are indicative of what?
transmembrane domain
what is the hydropathy window at residue 4?
average of indivudal hydropathies from 1-7
what is the hydropathy of residue 5?
average between 2-8
what are charged residues usually found to do?
expose themselves to water
blue colour
what does helix bundling allow for?
hydrogen bonding to glucose in channel region
in e.coli lactose permease, what is the switching believed to be due to?
change in protonation in AA salt bridge according to transmembrane proton gradient
in the calcium pump in SR, what is the phosphorylation of Ap351 believed to cause?
conformational change
changing exposure face of calcium binding domain
change affects affinity for calcium in binding site
allowing release into lumenal side of membrane
what is the human ABC transporter MDR1 responsible for?
tumour chemotherapy
what is the key AA in AQP-1 in all aquaporins
Asn-Pro-Ala
what do microbial cells require?
maintenance of high conc gradient of K to survive
what do valinomycin (K binding antibiotic) do?
selectively binds K via carbonyl oxygen atoms
valine-like side allows complex to pass through lipid bilayer
allows conc of K either side of membrane to equilibrate —> killing cell
