An alternative N-terminal fold of the intestine-specific annexin A13a induces dimerization and regulates membrane-binding.

ABSTRACT: Annexin proteins function as Ca²⁺-dependent regulators of membrane trafficking and repair that may also modulate membrane curvature. Here, using high-resolution confocal imaging, we report that the intestine-specific annexin A13 (ANX A13) localizes to the tips of intestinal microvilli and determined the crystal structure of the ANX A13a isoform to 2.6 Å resolution. The structure revealed that the N terminus exhibits an alternative fold that converts the first two helices and the associated helix-loop-helix motif into a continuous α-helix, as stabilized by a domain-swapped dimer. We also found that the dimer is present in solution and partially occludes the membrane-binding surfaces of annexin, suggesting that dimerization may function as a means for regulating membrane binding.

SUBMITTER: McCulloch KM 

PROVIDER: S-EPMC6416438 | biostudies-literature | 2019 Mar

REPOSITORIES: biostudies-literature