We can try to map the surface of a globular protein in two dimensions just like we depict the surface of the Earth in a world map. On such a map, the binding site of a molecule for other molecules of the same protein (for assembly into a multisubunit complex) can be marked. In the following "maps," two molecules of the protein can bind if the points a, b, and c on the surface of one molecule can align to points a′, b′, and c′ in the other molecule, respectively. Which map corresponds to a protein whose assembly gives rise to a helix? Hint: the other maps correspond to a dimer, a ring, and a linear filament.

Question

Quizplus · Accepted Answer

In contrast to dimers (D), rings (B), and straight filaments (A), which require a limited and special arrangement of the subunit binding interfaces, there are many possible arrangements that would give rise to various helical assemblies. The helix formed from this example will be left-handed.

We Can Try to Map the Surface of a Globular