Calcium-myristoyl switch, subcellular localization, and calcium-dependent translocation of the neuronal calcium sensor protein VILIP-3, and comparison with VILIP-1 in hippocampal neurons.

Neuronal calcium sensor (NCS) proteins including the subfamily of visinin-like-proteins (VILIPs) are involved in regulation of various signaling cascades. One molecular regulation mechanism is the calcium-myristoyl switch. VILIPs show a calcium-dependent membrane association in brain homogenates; however, differences in calcium-induced conformation changes and degree of membrane association are reported. Little is known about differences in the calcium-myristoyl switch in living cells leading to localization of VILIPs to distinct subcellular compartments. Therefore, we studied the calcium-dependent localization of green fluorescent protein (GFP)-tagged VILIP-3 in living cell lines and hippocampal neurons and compared it with that of GFP-VILIP-1. Interestingly, the observed fast and reversible calcium-myristoyl switch of VILIP-3-GFP and VILIP-1-GFP differed, e.g., in calcium-dependent translocation to Golgi membranes. Similarily, the calcium-dependent localization of endogenously expressed VILIP-3 and -1 in dendrites differed. Thus, VILIPs co-expressed in the same neuron show clear differences in calcium-dependent localization which may allow neurons a highly selective response to various calcium stimuli.