In the schematic drawing below, a protein is present on one side of a membrane i
ID: 97211 • Letter: I
Question
In the schematic drawing below, a protein is present on one side of a membrane in a high-enough quantity to induce curvature in this region of the membrane. In each of the following scenarios, indicate whether the protein would induce positive (P) or negative (N) curvature in the membrane
Your answer would be a three-letter string composed of letters P and N only, e.g. PPP.
• The protein inserts a hydrophobic domain into the membrane leaflet that is facing it. • The protein is a phospholipase that cleaves the head group in specific phospholipids. • The protein binds cooperatively to multiple phospholipids with very large head groups.
Explanation / Answer
PNP
In the first case, the hydrophobic domain insert causes the positive curvature because the insertion expands the membrane causing a positive or outward curvature
in the second case phospholipase the cleaves the head groups (phosphate containing) the molecule takes the shape of a cone, smaller at the head part and bigger at the tail (fatty acyl chain) part, giving a negaative curvature to the membrane.
similarly in the third case, binding of the protein at the head groups would increase the surface area at the head group giving it a positive curvature. this is similar to binding of the clathrin coats to the membrane in the vesicle formation for cellular trafficking.