Figure 1.

Protein Motion in a Branching Dendrite and the Associated Probabilities

A reconstructed dendritic arbor can be divided into compartments of equal length. The dendritic image was recorded using methods described in the STAR Methods section Image Acquisition. Each compartment can have one (A), two (B), or three (C) neighboring compartments. If a compartment has one neighboring compartment (A), the protein can jump back or stay, which is equivalent to a no-flux boundary condition. For two connected compartments (B), the probability of moving in either direction is equal. For a bifurcation (C), the probability of moving in either direction is determined by the cross-section or the circumference of the branches. These two options lead to fundamentally different outcomes: daughter branches are predicted to accumulate more protein relative to the mother dendrites (larger surface area than cross-section area) when the proteins move along the surface rather than in the dendrite.