Table 2. Relative potencies of AdA analogues at different IP3 receptor subtypes.
IP3R1 | IP3R2 | IP3R3 | |
IP3 | 1.02±0.02 | 0.9±0.30 | 1.1±0.30 |
Imidophostin | 0.78±0.15 | 0.78±0.08 | 0.81±0.04 |
Ribophostin | 0.82±0.18 | 0.96±0.20 | 1.06±0.07 |
Furanophostin | 0.92±0.13 | 0.83±0.14 | 1.25±0.05 |
Manno-AdA | 0.74±0.08 | 0.79±0.18 | 0.98±0.08 |
Xylo-AdA | −0.01±0.07 | −0.3±0.27 | 0.05±0.08 |
2′-dephospho-AdA | 1.24±0.33 | 1.60±0.18 | 1.68±0.16 |
3″-dephospho-AdAa | 4.03±0.09 | 4.47±0.30 | 4.13±0.14 |
From paired comparisons with AdA, the potency (ΔpEC50) of the analogues relative to AdA is shown for each IP3R subtype. Results are means ± SEM, with n provided in Table 1. ND, not determined. aBecause the very low affinity of 3″-dephospho AdA for IP3R made it impracticable to stimulate cells with a maximally effective concentration, ‘ΔpEC50’ for 3″-dephospho AdA was estimated by comparing concentrations of it and AdA that evoked the same sub-maximal Ca2+ release.