TABLE 3.
Modulation of kainate receptor properties by auxiliary subunits
Values at 2–3 significant figures are from the text or tables; when values are not reported, measurements were made from figures.
| Receptor | Subunit | EC50,PEAK c | EC50,SS d | τ-Deactivate e | τ-Desensitize e,g | τ-Recovery f,g |
Steady State/Peak
Current Ratio |
|---|---|---|---|---|---|---|---|
| μM | μM | ms | ms | ms | |||
| GluK1 a,b | – | 125–630 1,2 | 59 3 | 1.7 29 | 1.6–42 1,2,5-12,29 | 18–5100 7,10,29 | 0.01–0.04 10 |
| GluK1 | Neto1 | ↓ 4.4 2 | – | – | ↓ 2.6–5.2 2,7 | 301–1700 7 | 0.031 2 |
| GluK1 | Neto2 | ↓ 14 2 | – | 3.9 29 | ↑ 11–200 2,7,8,29 | ↓ 590 2,29 | ↑ 0.086 2 |
| GluK2a a | – | 234–1040 2,13-18 | 32–35 3,19 | 1.6–3.5 8,9,14,15,17-22 | 3.4–7 9,13,15,16,18-21,23-26 | 700–3020 8,13,15,16,20,21,23,25,27 | 0.001–0.008 2,13,19,20,23,24 |
| GluK2a | Neto1 | ↓ 60 25 | – | ∼1.6 22 | ↑ 32 25 | ↓ 240 25 | ↑ 0.06 25 |
| GluK2a | Neto2 | ↓ 77 2 | ↓ 15 19 | 2.6–3.3 8,19,22 | ↑ 15–24 8,9,19,26 | ↓ 800 8 | ↑ 0.01–0.027 2,19 |
| GluK1/5 b | – | 7.8 25 | 19 3 | – | 0.7–2.1 6,28,29 | 3800 29 | – |
| GluK1/5 | Neto1 | 5.2 25 | – | – | – | – | – |
| GluK1/5 | Neto2 | – | – | – | ↑ 3.3 29 | ↓ 450, ∼3800 29 | – |
| GluK2/4 | – | 43 25 | – | – | 4.4 27 | 2020 27 | – |
| GluK2/4 | Neto1 | ↓ 9.1 25 | – | – | – | – | – |
| GluK2/5 | – | 6.0–15 16,25 | 31 3 | 2.3–46 4,16, 29 | 1.8–6.0 4,6,8,9,16,25,26,29,30 | 1740–2700 16,25,29 | 0.02 4 |
| GluK2/5 | Neto1 | 5.0 25 | – | 3.9 4 | ↑ 6.2–8.2 4,25 | ↓ 250 25 | ↑ 0.064–0.082 4,25 |
| GluK2/5 | Neto2 | – | – | 5.0 29 | ↑ 11 26,29 | ↓ 61, ∼2500 29 | – |
| GluK3/5 | – | 6.0 25 | – | – | – | – | – |
| GluK3/5 | Neto1 | 4.8 25 | – | – | – | – | – |
a Unedited receptors or mutant kainate receptors with a glutamine at the Q/R/N site. All receptors are from rat except the human receptors reported in Alt et al. (2004).
b Values for GluK1-2a and GluK1-2b splice isoforms are pooled.
c EC50 was determined from the steady-state (SS) response from oocytes or transfected HEK cells.
d EC50 was determined from the peak response to rapid glutamate application in HEK cells or macropatches from Xenopus oocytes.
e If several exponentials described the deactivation or desensitization time course, the weighted mean time constant is given here.
f The time course of the recovery from desensitization was estimated from a single exponential.
g Onset and recovery from desensitization for GluK1-containing receptors are variable; the latter often shows two separable kinetic phases.
1 Sommer et al. (1992), 2 Fisher (2015), 3 Alt et al. (2004), 4 Straub et al. (2011a), 5 Swanson et al. (1997a), 6 Swanson et al. (1998), 7 Copits et al. (2011), 8 Vernon et al. (2017), 9 Copits et al. (2014), 10 Swanson and Heinemann (1998), 11 Larsen et al. (2017), 12 Ren et al. (2003c), 13 Traynelis and Wahl (1997), 14 Bowie (2002), 15 Kistler and Fleck (2007), 16 Barberis et al. (2008), 17 Perrais et al. (2009a), 18 Dawe et al. (2013), 19 Zhang et al. (2009b), 20 Heckmann et al. (1996), 21 Weston et al. (2006a), 22 Li et al. (2019b), 23 Bowie and Lange (2002), 24 Zhang et al. (2008e), 25 Fisher and Mott (2013), 26 Griffith and Swanson (2015), 27 Mott et al. (2010), 28 Swanson et al. (2002), 29 Straub et al. (2011b), 30 Fisher and Mott (2011).