Fig. 3.

Spectrin and adducin exhibit quasi-1D, periodic patterns in axons, quantitatively similar to that observed for actin. (A) 3D STORM image of βII-spectrin in axons. βII-spectrin is immunostained against its C-terminal region, which is situated at the center of the rod-like αII-βII spectrin tetramer. Inset: the yz cross-section of the boxed region showing the ring-like structure. (B) Histogram of the spacings between adjacent spectrin rings (N = 340). The red line is a Gaussian fit with mean = 182 nm and standard deviation = 18 nm. (C, D) Same as (A, B) but for βIV-spectrin, which is specifically located in the initial segments of axons. βIV-spectrin is immunostained against its N-terminal region, which corresponds to the ends of the spectrin tetramer. The red line superimposed on the histogram is a Gaussian fit with mean = 194 nm and standard deviation = 15 nm (N = 88). (E, F) Same as (A, B) but for adducin, an actin-capping protein. The red line superimposed on the histogram is a Gaussian fit with mean = 187 nm and standard deviation = 16 nm (N = 216).