Fig. 4.

Peak force required to unfold immunoglobulin (Ig) domains in the absence (Control) and presence (Calcium) of calcium, simulating activation of a muscle. Note the substantially increased force required to unfold and stretch immunoglobulin domains in the presence of calcium. Only the first 5 (of 8) immunoglobulin domains are shown, and only results where at least 5 domains unfolded were included in this analysis. Unfolding of 6 or more immunoglobulin domains was rare, and thus the number of observations was deemed inappropriate for statistical testing. Unfolding of 5 of the 8 immunoglobulin domains was observed in >300 individual test specimens for each of the calcium and the control conditions. Adapted from DuVall et al. (9) with permission from Springer Nature.