Figure 4.

Asymmetric localization of SpoIIQ and SpoIIIAH. (A) SpoIIQ (blue circles) is initially localized to the forespore membrane, whereas SpoIIIAH (green circles) is initially randomly distributed throughout the mother cell membrane. An interaction between SpoIIIAH and SpoIIQ across the forespore septum results in the colocalization of the two proteins at this polar structure. (B) Detailed view of the septum (as in the cell shown in A), showing the forespore membrane (FM) and the mother cell membrane (MM). SpoIIQ (“IIQ,” blue) and SpoIIIAH (“IIIAH,” green) interact in the intermembrane space mediating SpoIIIAH localization. Figure adapted from Blaylock et al. (2004) with permission.