Human β-III–spectrin and fly β-spectrin share functional pathways. (A) Scanning EM images of adult eyes from flies grown at 25°C. Insets show higher magnification images of the ommatidia field. Expression of fly β-spectrin carrying either the American (gmr-GAL4/+; FSPAM/+, II) or German (gmr-GAL4/FSPGM, III) SCA5 mutations in the adult fly eye results in a neurodegenerative eye phenotype. Overexpressing wild-type fly β-spectrin (gmr-GAL4/FSPWT, I) results in minor changes in the external morphology of the eye similar to the gmr-GAL4 control. (B, top) Total proteins from fly heads were analyzed by Western blotting using an antibody that recognizes fly β-spectrin. Tubulin was used as a loading control. The black line indicates that intervening lanes have been spliced out. (B, bottom) Bar graphs showing mean ratios of fly β-spectrin versus tubulin protein. The expression of fly β-spectrin in each transgenic line was similar and approximately twice the endogenous level of protein detected in the gmr-GAL4/+ driver line (P = 0.18, n = 4). Error bars indicate mean ± SEM (error bars); *, P = 0.18.