| Ca2+ dependent binding and activation of dormant ezrin by dimeric S100P . ^^^ Hereby we identify ezrin , a membrane / F actin cross linking protein , as a dimer specific S100P ligand . ^^^ S100P ezrin complex formation is Ca2+ dependent and most likely occurs within cells because both proteins colocalize at the plasma membrane after growth factor or Ca2+ ionophore stimulation . ^^^ The S100P binding site is located in the N terminal domain of ezrin and is accessible for interaction in dormant ezrin , in which binding sites for F actin and transmembrane proteins are masked through an association between the N and C terminal domains . ^^^ Interestingly , S100P binding unmasks the F actin binding site , thereby at least partially activating the ezrin molecule . ^^^ |