Figure 3.
Extra-cellular S100A9 activity A) S100A8/A9 sequesters zinc inhibiting the extracellular matrix degradation capacity of MMPs
B) S100A8/A9 or S100A9 serves to transport arachidonic acid (AA). Calcium binding to Apo-S100A9 (i) forms Ca2+-S100A9 (ii). The Ca2+-S100A9 (ii) protein binds to arachidonic acid forming the Ca2+-S100A9 –AA complex (iii). Zinc binding to Ca2+-S100A9 (ii) forms the Zn2+Ca2+-S100A9 complex (iv) and can no longer bind arachidonic acid.
C) S100A9 or S100A8/A9 binds to cell surface receptors initiating signal transduction cascades.