Biological Membranes Flashcards
Membrane composition
Asymmetric, heterogenous (protein and lipid)
Lipid clusters and lipid-protein aggregates
Functions of membranes
Barrier to toxins Transport and accumulation of nutrients Energy transduction Facilitation of cell motion Reproduction Signal transduction Cell cell interactions
Integral membrane proteins
Attached or anchored to the membrane
Globular proteins totally in the membrane
Peripheral membrane proteins
Generally globular, interact electrostatically/hydrogen bond with integral membrane proteins
Lipid anchor proteins
Proteins attached to membranes through lipid tails
Types of lipid anchored proteins
Amide linked myristoyl anchor
Thioester linked fatty acyl anchor
Thioester linked prenyl anchor
Glycosyl phosphatidylinositol anchor
Lipid anchor composition
Always myristic acid and N-terminal Gly residue
Prenyl
Long chain polyisoprene units
Target of isoprene units
C-terminal CAAX motif
Farnesyl
3 isoprene units
Geranylgeranyl
4 isoprene units
Types of lipid movements in membranes
Rotational diffusion, protrusion, flip-flop, lateral diffusion, bond vibrations, Gauche-trans isomerization
Membranes at low temperatures
Highly ordered, called solid ordered state, little motion, chains are fully extended, thickness is maximal
Membranes at high temperatures
Lots of motion, liquid crystalline phase or liquid disordered state, chains likely to be bent, gets thinner
Types of transporters
Passive diffusion, facilitated diffusion, active transport