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. Author manuscript; available in PMC: 2009 Nov 1.
Published in final edited form as: Biochim Biophys Acta. 2008 Aug 3;1778(11):2469–2479. doi: 10.1016/j.bbamem.2008.07.024

Fig. 7.

Fig. 7

Imperatoxin increases the probability of the Ryanodol substate. (A) Single-channel recordings of a ryanodol-modified RyR2 before and after addition of 50 nM IpTxA (Vm = +20 mV). "R" represents openings to the ryanodol-induced subconductance state. "i" represents opening to the IpTxA-induced substate during RyR2 full openings. "i + R" represents opening to the IpTxA-induced substate when the channel is being modified by ryanodol. (B) Amplitude histograms (grey area) and fits (black lines) at 0, +10, +20 and +30 mV of ryanodol-modified RyR2 before (upper panels) and after addition of 50 nM IpTxA (lower panels). (C) Probability (PRyanodol) of ryanodol-induced substates before (open circles) and after addition of 50 nM IpTxA (filled circles) as a function of holding voltage. (D) Diagram of states of RyR2 exposed to IpTxA plus ryanodol (40 min recording). The following states were considered: Full openings (Open), IpTxA-induced substate during full openings (IpTxA), Ryanodol modification (RyOH) and IpTxA-induced substate during ryanodol modification (RyOH-IpTxA). State probabilities (P) are given in parenthesis. Arrows represent observed unidirectional transitions from one state to another. Adjacent to each arrow is the respective absolute number of transitions.