Table 7

Ionic permeabilities relative to monovalent ions for glutamate receptors of known subunit composition

ReceptorPCa/PNa,Cs, K7-aPC1/PNa7-aPf (Ca)7-b
GluR12.340.032 Burnashev et al., 1995
GluR20.14 Burnashev et al., 1996
GluR1/GluR20.05∼00.005 Burnashev et al., 1995,1996
GluR40.039 Burnashev et al., 1995
GluR6(R)7-c 0.127-d 0.740.0027-e Burnashev et al., 1995, 1996
GluR6(Q)0.21–1.2∼00.0167-e Egebjerg and Heinemann, 1993; Burnashev et al., 1995, 1996
GluR6(R)/GluR6(Q)∼00.0067-f Burnashev et al., 1995, 1996
NR1-1a/NR2A3.10–110.1–0.19 Burnashev et al., 1995; Wollmuth et al., 1996; Sharma and Stevens, 1996b;Schneggenburger, 1996, 1998
NR1-1a/NR2B170.175 Iino et al., 1997; Schneggenburger, 1996
NR1-1a/NR2C2.230.082 Burnashev et al., 1995
  • Na+ and Cs+ are considered equally permeable.

  • 7-a Lewis equation derived from the Goldman-Hodgkin-Katz equation.

  • 7-b Proportion of whole-cell current carried by Ca2+determined from simultaneous measurement of whole-cell current and Ca2+ fluorescence.

  • 7-c Results are shown only for studies which either directly measure Ca2+ flux or take into consideration the C1permeability.

  • 7-d Not significantly different from zero.

  • 7-e Editing of transmembrane region 1 had no effect fractional Ca2+ current through GluR6(R), but slightly decreases fractional Ca2+ current through GluR6(Q).

  • 7-f Expressed at a ratio of 1∶1.