Concanavalin A receptors in the plasma membrane of rat liver cells: comparative electron microscopic studies on normal cells and on cells in vivo transformed by diethylnitrosamine.

The Concanavalin A receptors at the cell surface of normal rat liver cells and of those in vivo transformed by diethylnitrosamine were comparatively studied by electron microscopic cytochemistry. Besides different agglutinability of the cells a variable surface staining of the cells by the Con A-peroxidase reaction (BERNHARD and AVRAMEAS 1971) was observed. After performance of the cytochemical reaction on living normal rat liver cells in situ a continuous cell surface staining was seen. In transformed rat liver cells a marked tendency for patchy distribution of the Con A label at the cell surface occurred. Furthermore, internalisation of Con A-peroxidase labeled plasma membrane segments was visible in the transformed cells. A similar variable labeling by Con A-peroxidase reaction occured also in the "basal" plasma membrane of normal and transformed rat liver cells. The results are discussed with respect to the importance concerning the mobility of lectin receptors and membrane stability.