The Fas receptor (FasR)-mediated apoptotic pathway has recently been shown to be regulated by Ca2+ fluctuations in the cell, specifically through calmodulin (CaM).  CaM contains four EF-hand motifs and upon Ca2+ binding, a conformational change is elicited, allowing FasR binding. The calmodulin-binding sequence of FasR has been suggested through a pull-down assay. However, the biochemistry of such an interaction has not been explored. Here we used synthetic peptides and recombinant CaM and Troponin C chimeras (1TnC, 2TnC, 3TnC, and 4TnC), and separately determined their thermodynamic and kinetics parameters using isothermal titration calorimetry (ITC) and fluorescence. Our data indicated that the 3rd and 4th EF-hands of CaM preferentially interact with the peptide (WTLSQVKGFVRKNGVNE). Currently, we are investigating such a preferential binding using trypsin-digested CaM and/or modified FasR peptides.

Interaction of Fas receptor peptides with Calmodulin and its derivatives

245th National Meeting (2013)

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