Synthesis of a brain-specific protein (S100 protein) in a lectin-resistant mutant of a rat glial cell line (C6).

The synthesis of S100 protein increases toward the end of the exponential phase of growth of clonal rat glial cells C6 in monolayer culture. Moreover the synthesis of this protein can be increased by treatment of C6 cells with the lectin succinylated concanavalin A (succinyl ConA). In order to study the relationship between these two inductions of S100 protein we have isolated a cell line resistant to ConA from a population of C6 cells. The resistant cells (C6-ConAR) have less succinyl ConA receptors than C6 cells. In contrast to C6 cells, the synthesis of S100 protein does not increase in C6-ConAR cells after treatment with succinyl ConA. However in both cell types the synthesis of S100 protein increases toward the end of the exponential phase of growth. These results suggest firstly that the induction of S100 protein in C6 cells by succinyl ConA is mediated by an interaction of the lectin with its membrane receptors and secondly that the initial steps in the induction of S100 protein by the lectin are different from the initial steps in the induction of this protein which occurs toward the end of the exponential phase of growth in monolayer culture.