RYR1 vs. RYR2). Given the voxel size of the images, the maximal plasma membrane area covered by each punctum on average was 0.05–0.160 µm2 for RYR1 and 0.06–0.18 µm2 for RYR2 (see Materials and methods for calculation). Based on the results of reverse transcription PCR and immunocytochemistry, we conclude that (a) RYR3 is present, but at lower abundance and further inside the cells, especially in the perinuclei regions, and (b) RYR1 and RYR2 represent the major forms of RYRs and form puncta in these cells.
