Fig. 5.

Internalization of NCX1-Halo fusion protein after labeling. A: NCX1 with an extracellular Halo fusion near the NH₂-terminal glycosylation site was expressed in iCell Cardiomyocytes for 4 days. The Halo tag was then labeled with Alexa488 Halo label and iCells were imaged at fixed intervals for 12 h. Over this time a nearly linear increase of cytoplasmic punctae occurred, indicative of NCX1 internalization. Scale bar = 20 μm. B: plot of the average number of defined nonnuclear punctae. The best fit to an asymptotic exponential function gives a time constant of 42 h for NCX1 loss from the cell surface.