The role of direct heparan sulfate interactions and Ca2+ complexation for cell-surface restricted Hedgehog transport in vitro
Hedgehog (Hh) proteins act as morphogens that transmit positional information to embryonic cells to steer their differentiation. All vertebrate and invertebrate Hh morphogen family members firmly tether to the outer plasma membrane leaflet of their producing cells where they form multimers. How these multimers are transported to the receiving cells is still unknown.
What is known is that cell surface Heparan sulfate proteoglycans (HSPG) are essential for Hh morphogen function. It is also known that two Ca2+ ions of unknown function are complexed in all Hh family members close to the HS binding site.
I am characterizing the nature of the Hh/HSPG interaction and its dependency on Ca2+ complexation by biochemical means.