week 2 Flashcards
three classes of membrane prot
integral
peripheral
lipid anchored
how are proteins distributed across a mem
assymetrically
how are peripheral mem prot interact with the mem
via weak non covalent bonds
they are polar
are peripheral mem prot dynmaic>
yes. the often are associated with movement either to or from the mem
roles of peripheral prot
-signal transduction
-mechanical suport (shape mem)
-anchor for integral mem prot
-act as enzymes
which proteins are responsible for RBC shape. where are they found
spectrin
found on the integral (inside) to give concave shape
lipid anchored prot location
-on the extracelluar or cytoplasmic side
lipid anchored prot mem attachment
via covalent bonds to a lipid mole
2 types of lipid anchored prot
-GPI anchored prot
-Hydrocarbon chains embedded in the bilayer
GPI anchored prot
Glycosyl-Phosphatidyl Inositol linkage
-only ont he extra cell side
- role= cell adhesion and receptors
hydrocarbon chains embedded in the lipid bilayer
direct linkage
on the cyto and extra cell sides
signal transduction role
phospholipid dynamics
-easy and fast later movement
- restricted flip flop movement. this is because it is thermodynamically unfavourable due to the requirement of the polar head needing to pass through the non polar ‘tail region’
flippase
the enzyme responsible for establishing membrane asymmetry
which lipid type can flip flop the easiest
cholesterol. due to its small polar head and large non polar ring structure
membrane prot dynamics
movement of particles via
1) random diffusion
2) immobilized (no movement)
3) particular direction (motor prot)
4) restricition by other integral mem pot
5) restriction via mem skeleton
6) restrain via extracellular materials
