Figure 7.

Basic amino acids at the M770 position act as surrogate cations. a, Left, Raw data traces showing anion substitutions in which Na⁺ is the major cation (patch 04130p2). There is an acceleration of decay kinetics when Br⁻ is replaced with Cl⁻ and NO₃⁻. Right trace shows the same experiment as left but with Rb⁺ as the major cation (patch 06209p1). Note that anion substitutions do not change decay kinetics in the presence of Rb⁺. b, An extended series of anion substitutions with either Na⁺ (black bars) or Rb⁺ (white bars) as the dominant cation. There is no change in decay kinetics when anions are substituted in Rb⁺ in contrast to Na⁺. Data are mean ± SEM for at least six patches in each anion with Na⁺ or Rb⁺ as the major cation. c, The effect of changing the external Na⁺ (filled squares) and Rb⁺ (open circles) concentrations on the decay kinetics of wild-type GluR6 (left) and GluR6_M770K (right) receptors. Note that the decay kinetics GluR6_wt matches that of GluR6_M770K only when Rb⁺ ions are used.