Cordon Bleu (Cobl) is a WH2-containing protein believed to act as an actin nucleator. We show that it has a very specific localization in epithelial cells at the basal region of microvilli, a localization unlikely to be involved in actin nucleation. The protein is localized by a central region between the N-terminal COBL domain and the three C-terminal WH2 domains. Ectopic expression of Cobl shortens apical microvilli, and this requires functional WH2 domains. Proteomic studies reveal that the COBL domain binds several BAR-containing proteins, including SNX9, PACSIN 2/syndapin 2, and ASAP1. ASAP1 is recruited to the base of microvilli by binding the COBL domain through its SH3. We propose that Cobl is localized to the basal region of microvilli both to participate in length regulation and to recruit BAR proteins that associate with the curved membrane found at the microvillar base.
© 2014 Wayt and Bretscher. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).