Fig. S7.
Casq1-like content in extratriadic SR (supports Figs. 4–6). (A–C) Examples of cisternae with granular content attributed to polymeric Casq1. Red arrows indicate their presence in TC, and yellow arrows indicate their presence in longitudinal extratriadic SR cavities. (D) Arrows indicate examples of SR content of an ambiguous nature. In all cases, muscles had not been stimulated or subjected to chemical depletion. (E–H) Examples of structure in muscles fixed after fatiguing stimulation that led to partial depletion ([Ca2+]SR measured at 45% of resting level 5 min before fixation). The granular content outside triads, again indicated by yellow arrows, appears to be greater in the stimulated cells, but the abundance of SR cisternae with ambiguous content precluded the quantification of differences. (Scale bars: 0.1 μm.)