Synaptopodin regulates the actin-bundling activity of α-actinin in an isoform-specific manner
J. Clin. Invest. Katsuhiko Asanuma, et al. 115:1188 doi:10.1172/JCI23371 [
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Figure 3Synpo-short and Synpo-long interact with α-actinin-4 and α-actinin-2. (
A) Coimmunoprecipitation experiments showing that endogenous synaptopodin interacts with α-actinin-4 in podocytes. Left: Immunoprecipitation with anti-synaptopodin (Synpo). Right: Immunoprecipitation with anti–α-actinin-4. No interaction was found with a control antibody. (
B) GFP-tagged Synpo-long and Synpo-short coimmmunoprecipitated with FLAG-tagged α-actinin-4 but not with the FLAG control. (
C) In a converse experiment, GFP-tagged α-actinin-4 coprecipitated with FLAG–Synpo-alt and FLAG–Synpo-short. No interaction was found with the GFP control. (
D) FLAG–Synpo-alt and FLAG–Synpo-short also interact with GFP-tagged α-actinin-2. (
E) Synpo-short contains 2 independent nonoverlapping interaction sites (gray boxes) for α-actinin-4 that are contained in AA 300–550 and 550–691. In contrast, the SP1 fragment and the FLAG control do not interact with α-actinin. (
F) Synpo-alt also contains 2 independent nonoverlapping α-actinin interaction sites that are localized in AA 103–159 and 182–227 of the Synpo-alt fragment. Hence, Synpo-long contains 4 α-actinin interacting sites, whereas Synpo-short contains only 2 α-actinin interacting sites.
