An immunoelectron microscopic study on the distribution of a cell surface-associated adhesive glycoprotein synthesized by rat ascites hepatoma cells

As previously described, a cell surface-associated adhesive factor (AF) was separated from differentiated rat ascites hepatoma AH136B cells (forming cell islands in vivo) and highly purified by chromatography. AF synthesis by the cells was investigated by means of ultrastructural immunoperoxidase cytochemistry. Its synthesis and localization in vivo were observed in the perinuclear spaces, the rough endoplasmic reticulum, the Golgi apparatus, the smooth-membranous vesicles, and the contact region of basolateral cell surfaces of the cells in the islands, and also in the intercellular spaces. No AF synthesis was detectable in the nucleus, the free ribosomes, the mitochondria or the apical non-contacting cell surfaces. Similar features of AF synthesis and localization were also induced by dissociated AH136B cells in vitro. Upon adhesion of such recovered cells, AF was also localized at the contact surface of the adjacent cells, but not at the non-contacting free surface.