FIG. 8.
Model for CNF receptor binding. In this model, HSPG is part of the receptor for CNF1 and additionally acts as the receptor for CNFY. CNFY binds to a subtype of HSPGs (called HSPGa) present on HeLa cells, thereby blocking HSPG-dependent binding of CNF1 to the laminin receptor precursor p37 (p37LRP). Because HSPGs are found not only in complex with p37, binding of CNF1 has no influence on the uptake of CNFY. CNFY may not bind to a different subtype of HSPGs (HSPGb), expressed by nonresponsive cell lines like Caco-2 cells.