Figure 1.

The above graphic illustration of the hypothetical pan-junctional SR features multiple nanojunctions between the SR, on the one hand, and the PM, mitochondria and lysosomes, on the other. Each nanojunction is identified with a number corresponding with its description in the text below. The ion transporter (codes shown below the picture) content of each junction is based on experimental evidence in the literature, which varies from solid to hypothetical. ECS: extra-cellular space; cyt: cytoplasm.