[Insulin catabolism by transformed, cultivated mouse fibroblasts (L-cells)]

Cultivated, transformed mouse fibroblasts (L-cells) are endowed with enzyme systems for insulin breakdown that are comparable to those of many other types of non-dedifferentiated insulin target cells (time and substrate dependence, Km value). It cannot yet be decided, however, which of the potential enzyme systems (thiolproteindisulfide-oxidoreductase (TPO) [E.C. 1.8.4.2] or proteinase) is prevalent in insulin breakdown in intact L-cells. Despite the lack of typical target symptoms for insulin, the cultivated L-cell could provide an appropriate experimental model for the insulin metabolism.