Study BMB 464 Exam 1 Flash Cards

 
Pile Management Card
BMB 464 Exam 1

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Where are sugar modifications found on transmembrane proteins (outside of the plasma membrane or inside, lumenal side of Golgi or cytoplasmic side)?
Glycosylated on the noncytoplasmic face (extracellular face)
Does the ER lumenal or cytoplasmic portion of a protein destined for the plasma membrane end up on the cell surface?
N-terminus in the ER lumen will end up on the cell surface
If I tell you that a protein is an integral membrane protein, but that no portion of the
polypeptide chain passes through the bilayer, how might this protein be imbedded in the
membrane?
Covalently linked to other molecules that have a hydrophobic anchor in the bilayer
How big would you expect these regions to be (how many amino acids should they span) for the hydrophobicity plot?
~20ish aas
Formation of the correct disulfide bonds occurs in the _____________ through the action of ____________.
-lumen of the ER
-protein disulfide isomerase
reduction in the cytoplasm is achieved
primarily by _______________.
glutathione,a tripeptide composed of
gamma-glutamyl-cysteinyl-glycine
O-linked glycosylation
on serine and threonine occurs in the Golgi
N-linked glycosylation
on asparagine in ER and then modified in the Golgi
noncytoplasmic face info
-extracellular face
-Glycosylated
cytoplasmic face is the...
lumenal
ER protein destinations
• N-terminus in the ER lumen will end up on the cell surface
• N-terminus in the cytoplasm will end up in the cytoplasm
Integral membrane proteins
-require detergent to dissociate
-attached through some kind of hydrophobic connection with hydrophobic core of the bilayer
-Almost always composed of alpha helix that passes completely through the bilayer
-generally composed of hydrophobic amino acids to span the hydrophobic core of the bilayer
• Hydrogen bonding between neighboring peptide bonds
masks the hydrophilic parts so they can reside in the hydrophobic part of the bilayer
-or, can be covalently linked to other molecules that have a hydrophobic anchor in the bilayer
beta barrel structure
-H bonding between peptide bonds of neighboring strands mask
hydrophilic residues
Triton
-dissolves membranes and solubilizes proteins by binding the membrane
associated region
-usually does not inactivate proteins
SDS
-denatures and separates subunits
-inactivates
Detergents
-amphipathic
-coat hydrophobic surfaces.
-ex: SDS and Triton X-100
Peripheral membrane proteins
-dissociate with high salt or pH changes.
-ionic, not covalent, interactions
inositol phospholipids
involved in cell signaling
Cholesterol
• -OH is the polar head group
• only lipid that can spontaneously flip from one leaflet to another
• only in animal cells
• affects fluidity of membrane
micelle
-forms from lipid molecule with one fatty acid tail
4 major components of PM
1. phosphatidylserine PS
2. phosphatidylethanolamine PE
3. phosphatidylcholine PC
4. sphingomyelin
How thick is the bilayer?
about 5 nm thick
Prokaryote diameter
1 to 10 microns
Eukaryote diameter
5 to 100 microns
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