Infantile restrictive cardiomyopathy: cTnI-R170G/W impair the interplay of sarcomeric proteins and the integrity of thin filaments
Fig 4
cMyBPC-C0C2 interacts with cTn and impacts its binding to thin filaments.
(A) Binding of troponin containing wildtype (WT, black) cTnI or R170G/W (gray or white, respectively) to reconstituted thin filaments depending on the presence of cMyBPC-C0C2 analyzed by cosedimentation. Data are given as amount of bound cTnI relative to total cTnI in the sample ±SEM, normalized to wildtype cTnI in the absence of C0C2 (WT -C0C2, n = 15-18 each, * indicates statistical significance with P<0.05; *** indicates statistical significance with P<0.001). (B) Interaction of cMyBPC-C0C2 with troponin complexes containing cTnI-variants (mean normalized fluorescence ±SEM, AU: arbitrary units; wildtype: solid line, black circles; R170G: dotted line, gray circles; R170W: dashed line, white circles) as measured by MST. Data were fitted to the Hill function to determine EC50 (n = 5 for WT, n = 6 for R170G and R170W each). (C) Interaction of cMyBPC C0C2 with cTnI wildtype or R170G/W (as in panel B, n = 6 for WT, n = 5 for R170G and n = 7 for R170W). (D) Interaction of cMyBPC C0C2 with cTnT (mean ±SEM, n = 5). (E) No significant change in fluorescence (mean ±SEM, n = 4) and thus in cMyBPC thermophoresis was found in the presence of 100 μM cTnC, confirming the absence of an interaction.