What holds Ras at the inner surface of the plasma membrane?
A)weak interactions with the phospholipid head groups
B)weak interactions with integral membrane proteins
C)hydrophilic interactions of the Ras protein with the interior of the phospholipid bilayer
D)attachment to a lipid group that is embedded in the inner leaflet of the bilayer
E)attachment to a carbohydrate group that is embedded in the inner leaflet of the bilayer

Question

Quizplus · Accepted Answer

Ras is a lipid-anchored protein that contains a lipid group, such as a farnesyl or geranylgeranyl group, that is embedded in the inner leaflet of the plasma membrane. This lipid group is what holds Ras at the membrane surface, as it is hydrophobic and interacts strongly with the hydrophobic tails of the phospholipids in the membrane. Weak interactions with other molecules, such as integral membrane proteins or the phospholipid head groups, would not be sufficient to strongly anchor Ras at the membrane surface.

What Holds Ras at the Inner Surface of the Plasma