Characterization of the lipid binding properties of Otoferlin reveals specific interactions between PI(4,5)P2 and the C2C and C2F domains.

ABSTRACT: Otoferlin is a transmembrane protein consisting of six C2 domains, proposed to act as a calcium sensor for exocytosis. Although otoferlin is believed to bind calcium and lipids, the lipid specificity and identity of the calcium binding domains are controversial. Further, it is currently unclear whether the calcium binding affinity of otoferlin quantitatively matches the maximal intracellular presynaptic calcium concentrations of ∼30-50 μM known to elicit exocytosis. To characterize the calcium and lipid binding properties of otoferlin, we used isothermal titration calorimetry (ITC), liposome sedimentation assays, and fluorescence spectroscopy. Analysis of ITC data indicates that with the exception of the C2A domain, the C2 domains of otoferlin bind multiple calcium ions with moderate (Kd =

SUBMITTER: Padmanarayana M 

PROVIDER: S-EPMC4144714 | biostudies-literature | 2014 Aug

REPOSITORIES: biostudies-literature