Fig. 2.

Immunoblot and caffeine-induced Ca²⁺ release by HEK293 cells expressing wild-type (WT) and mutant type 1 ryanodine receptors (RyR1s). A: immunoblots of HEK293 cells transfected with pCMV5 vector and RyR1-WT expression vector (left), and 565 kDa RyR1-Q3970E, RyR1-Q3970K, and RyR1-WT (right). The blots identified the RyR1 protein band by its absence from the pCMV5 vector-transfected sample (left). B: Ca²⁺ transients in HEK293 cells expressing RyR1-WT (top), RyR1-Q3970E (middle), and RyR1-Q3970K (bottom) as changes of Fluo-4 fluorescence before and following the addition of 8 mM caffeine (arrow) to the bath solution. AU, arbitrary units.