Calcium- and myristoyl-dependent subcellular localization of the neuronal calcium-binding protein VILIP in transfected PC12 cells.

Wild-type neuronal calcium-binding protein VILIP (visinin-like protein), and a myristoylation mutant of VILIP which lacks the consensus sequence for N-terminal myristoylation, have been stably transfected in PC12 cells. Immunocytochemical studies of VILIP-transfected PC12 cells have revealed the wild-type VILIP is strongly concentrated at the cell membrane, particularly at cell-cell contact sites, but is also distributed throughout the cytosol at moderate levels. In contrast, myristoylation-mutant VILIP shows a more even distribution, with significantly less association at cell-cell contact sites. Western blot analysis of subcellular fractions has shown that wild-type VILIP associates in a calcium-dependent manner with membrane fractions, whereas the myristoylation mutant only weakly associates with this fraction. Therefore, a calcium-myristoyl switch seems to be a major, but not sole determinant for the association of VILIP with membranes in living cells.