Membrane proteins

Question 1

what is the evidence for membrane proteins

Answer 1

functional- facilitated diffusion, ion gradients, specificity of cell responses
biochemical- membrane fractionation + gel electrophoresis, freeze fracture

Question 2

how can proteins move in bilayer

Answer 2

conformational change
rotational
lateral
NO FLIP FLOP

Question 3

why can’t proteins flip flop

Answer 3

because amounts of hydrophilic structure that’s exposed to the aq environment is too big and too energetically unfavourable to flip.

Question 4

how are proteins restricted from moving

Answer 4

lipid rafts
aggregates -assemblies of proteins
tethering- some membrane proteins might adhere to molecules in the substratum restricting mobility.As well as interaction with cytoskeleton
interaction with other cells

Question 5

what are then two types of membrane proteins

Answer 5

integral and peripheral

Question 6

state some features of peripheral proteins

Answer 6

bound to surface
electrostatic and hydrogen bond interactions
removed by changes to pH or ionic strength

Question 7

state some features of integral proteins

Answer 7

interact extensively with hydrophobic domains of the lipid bilayer
cannot be removed by manipulation of pH and ionic strengths
removed by agents that compete for non-polar interactions e.g detergents and organic solvents