The neuronal EF-hand Ca(2+)-binding protein VILIP: interaction with cell membrane and actin-based cytoskeleton

VILIP is a member of the visinin/recoverin family of neuronal EF-hand Ca(2+)-binding proteins. Cell fractionation revealed cytoplasmic, membrane- and cytoskeleton-associated pools of VILIP. The association with the cytoskeletal protein fraction is Ca(2+)-dependent and may be mediated by direct interaction with actin. This is concluded from the observations that (i) Ca(2+)-loaded recombinant VILIP binds actin in an overlay assay; (ii) in the presence of Ca(2+), beta-actin co-immunoprecipitates with native VILIP from brain extracts, and (iii) actin and VILIP are co-localized in PC12 cells stably transfected with VILIP cDNA. The interaction of VILIP with the cortical cytoskeleton through actin may facilitate a Ca(2+)-dependent recruitment of VILIP to the cell membrane.