VIGILIN IS A CYTOPLASMIC PROTEIN - A STUDY ON ITS EXPRESSION IN PRIMARY-CELLS AND IN ESTABLISHED CELL-LINES OF DIFFERENT SPECIES

A fusion protein composed of about two vigilin domains and beta-galactosidase was used to raise polyclonal antibodies which were affinity-purified and employed for immunoblotting and immunohistochemistry. A protein of an apparent molecular mass of 155 kDa could be stained in extracts of a variety of cells from different species and organs. Immunohistological studies on single cells showed that vigilin is accumulated in the cytoplasm. During in vitro maintenance of primary cell cultures, as well as of a growth-factor-dependent cell line, vigilin expression decreases and ceases in senescent cells. In contrast, vigilin is constitutively expressed in all other transformed cell lines of various origin studied so far. Vigilin expression can be induced in peripheral blood lymphocytes by mitogen stimulation. These observations suggest an involvement of vigilin in processes of cell activation. Immunoblot experiments demonstrating the presence of vigilin in a broad range of eukaryotes, indicate a high degree of evolutionary conservation.