Lecture Set 8 Flashcards
What are the three ways proteins interact with membranes?
1) Integral –> hydrophobic core regions
2) Peripheral –> non-covalently bound to membrane lipid
3) Lipid-anchored –> covalently bonded to membrane lipids
What is the difference between integral/peripheral
functionally: integral can only be removed through detergents
peripheral can be removed by chelation of Ca2+, addition of urea, change in pH or ionic strength
What are the four modifications of lipid anchored proteins?
1) palmitation
2) Meristylation
3) prenylation
4) GPI –> glycosylphosphatidylinositol
palmitation and meristylation = acetylation
first three only occur on cytosolic face
What are the 4 different types of integral membrane proteins?
type 1 = N-terminal on exoplasmic face
type 2 = C-terminal on exoplasmic face
type 3 = multi-pass protein
type 4 = multiple single pass proteins
what does the transmembrane sequence look like?
alpha-helix, hydrophobic, can be a beta-barrel
How can you test for protein motility in the membrane?
fluoresence tagging, then combine with a hybrid cell through virus-induced fusion, then watch mixture of fluorescent proteins
where are oligosaccaride chains found on proteins?
noncytosolic side
How can cell surface protein movement be restricted?
1) attachment to extracellular matrix
2) attach to cell cortex
3) interact with proteins on other cells
4) junctional barriers (ex. tight junctions)