Membrane 2 Flashcards
three ways proteins interact with membranes
integral, peripheral and lipid linked
Integral Proteins
- Do they extend through the bilayer?
- are the amino acids polar or non-polar?
- what configuration do they adopt across the bilayer
- yes
- non-polar
- alpha-helical
Three examples of integral proteins
alpha helix, helical bundle, beta-barrel
are integral membrane proteins permanently attatched?
yes
are non-membrane associated domains hydrophilic or hydrophobic?
hydrophilic
how can membrane topology be deduced?
from the amino acid sequence
where are beta-barrels normally located?
in outer membranes of bacteria, mitochondria and chloroplasts
What kind of diffusion does glucose transporters allow
facilitated diffusion
Structure of glucose transporters
12 transmembrane alpha-helices
example of a peripheral membrane protein
phospholipases
What do phospholipases do
group of enzymes that hydrolyse phospholipids, releasing a variety of products
what must phospholipases do first to allow phospholipid hydrolysis to occur
must bind to the phospholipid interface to allow phospholipid hydrolysis to occur
define lipidation
addition of hydrophobic molecules to a protein
three types of lipid linked modification
palmitoylation, myristylation and prenylation
why is myristoylation important
allows weak protein-protein and protein-lipid interactions
what does palmitoylation enhance?
hydrophobicity
example of a lipid anchor
GPI
what do prenylation do
facilitates attachment to cell membranes
What do GPI anchors do
anchors a modified protein in the outer leaflet of a cell membrane
