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. 2011 Jan 31;6(1):e16197. doi: 10.1371/journal.pone.0016197

Figure 8. Rac3 is immunoprecipitated with the ABD of βI-spectrin and might mediate its effects on dendritic spines.

Figure 8

A, Rac3 is specifically enriched in immunoprecipitates of detergent extracts of cortical cell cultures generated with antibodies to βI-spectrin. The input sample (lane 1) contained easily detected amounts of βI-spectrin and Rac1 but relatively little Rac3. Immunoprecipitation with an anti-βI-spectrin antibody (lane 2) specifically concentrated βI-spectrin and Rac3, but did not precipitate Rac1. Neither GTPase was detected after immunoprecipitation with a non-immune rabbit IgG (lane 3). B, GFP images of CA1 pyramidal cell dendrites co-expressing GFP and the ABD of βI-spectrin either with or without dominant negative (DN) Rac3, and co-expressing GFP with wild type Rac3. Scale bar = 10 µm. C, Pooled data illustrate the effects on the mean spine head diameter, calculated from GFP images (n = 100–300 spines/neuron, 2–5 neurons/group, p<0.001, ANOVA with Sheffe's test). Spines in cells expressing the ABD of βI-spectrin had larger heads than cells expressing GFP alone, but not when co-expressing dominant negative Rac3. Expression of wild-type Rac3 resulted in spines with large heads, thus mimicking the effects of the ABD of βI-spectrin.