Table I. Biophysical parameters for... | Rockefeller University Press

Table I.

Biophysical parameters for hippocampal neurons, native I_DR currents, and cloned Kv2.1 channels

Treatment		Hippocampal neurons			Native I_DR			Cloned Kv2.1			Cloned K470Q
	Dose	Vm	Rin	Ff	V_1/2	V_s	I_PEAK	V_1/2	V_s	I_PEAK	V_1/2	V_s	I_PEAK
	pM	mV	MΩ	Hz	mV		pA/pF	mV		pA/pF	mV		pA/pF
None		−58 ± 4	65 ± 4	5 ± 2	22 ± 2	14 ± 3	72 ± 12	21 ± 4	9 ± 1	245 ± 16	3 ± 3	13 ± 3	382 ± 24
SUMO2₉₂	75	−50 ± 4^a	87 ± 5^a	15 ± 5^a	40 ± 3^b	13 ± 2	20 ± 7^b	36 ± 4^b	10 ± 2	62 ± 10^b	4 ± 4	11 ± 6	374 ± 21
SUMO3₉₂	75	−48 ± 6^a	86 ± 5^a	14 ± 4^a	39 ± 4^b	12 ± 4	21 ± 7^b	36 ± 6^b	9 ± 3	62 ± 11^b	4 ± 4	11 ± 7	373 ± 20
SUMO1₁₀₁	7	−52 ± 3	73 ± 6	8 ± 2	28 ± 3^a	12 ± 3	35 ± 8^b	28 ± 3^a	12 ± 3	100 ± 15^b	4 ± 8	13 ± 4	378 ± 17
SUMO1₁₀₁	75	−49 ± 4^a	84 ± 5^a	13 ± 3^a	39 ± 3^b	12 ± 3	22 ± 8^b	37 ± 4^b	10 ± 2	61 ± 8^b	4 ± 3	11 ± 4	375 ± 19
SUMO1₁₀₁	250	−47 ± 6^a	86 ± 5^a	14 ± 4^a	37 ± 4^b	11 ± 4	21 ± 9^b	35 ± 6^b	9 ± 4	63 ± 9^b	3 ± 4	12 ± 6	370 ± 24
SUMO1₉₅	75	−60 ± 5	63 ± 6	6 ± 4	20 ± 3	13 ± 3	73 ± 7	20 ± 3	13 ± 3	249 ± 11	5 ± 4	13 ± 3	372 ± 15
denatured SUMO1₁₀₁	75	−57 ± 5	64 ± 3	5 ± 2	19 ± 4	12 ± 3	70 ± 8	20 ± 5	11 ± 4	240 ± 20	4 ± 4	13 ± 3	378 ± 18
SENP1	250	−65 ± 5^a	51 ± 5^a	1 ± 2^a	3 ± 4^b	13 ± 4	100 ± 18^b	1 ± 4^b	10 ± 2	370 ± 23^b	4 ± 4	13 ± 4	366 ± 21
SENP1-C603S	250	−57 ± 5	64 ± 6	6 ± 3	20 ± 4	13 ± 4	72 ± 14	19 ± 6	9 ± 3	249 ± 17	4 ± 3	13 ± 3	388 ± 21
Δ SENP-SUMO		16 ± 6	33 ± 8	12 ± 4	36 ± 5	0 ± 5	78 ± 20	36 ± 6	0 ± 3	309 ± 24	0 ± 5	0 ± 6	9 ± 28

Treatment		Hippocampal neurons			Native I_DR			Cloned Kv2.1			Cloned K470Q
	Dose	Vm	Rin	Ff	V_1/2	V_s	I_PEAK	V_1/2	V_s	I_PEAK	V_1/2	V_s	I_PEAK
	pM	mV	MΩ	Hz	mV		pA/pF	mV		pA/pF	mV		pA/pF
None		−58 ± 4	65 ± 4	5 ± 2	22 ± 2	14 ± 3	72 ± 12	21 ± 4	9 ± 1	245 ± 16	3 ± 3	13 ± 3	382 ± 24
SUMO2₉₂	75	−50 ± 4^a	87 ± 5^a	15 ± 5^a	40 ± 3^b	13 ± 2	20 ± 7^b	36 ± 4^b	10 ± 2	62 ± 10^b	4 ± 4	11 ± 6	374 ± 21
SUMO3₉₂	75	−48 ± 6^a	86 ± 5^a	14 ± 4^a	39 ± 4^b	12 ± 4	21 ± 7^b	36 ± 6^b	9 ± 3	62 ± 11^b	4 ± 4	11 ± 7	373 ± 20
SUMO1₁₀₁	7	−52 ± 3	73 ± 6	8 ± 2	28 ± 3^a	12 ± 3	35 ± 8^b	28 ± 3^a	12 ± 3	100 ± 15^b	4 ± 8	13 ± 4	378 ± 17
SUMO1₁₀₁	75	−49 ± 4^a	84 ± 5^a	13 ± 3^a	39 ± 3^b	12 ± 3	22 ± 8^b	37 ± 4^b	10 ± 2	61 ± 8^b	4 ± 3	11 ± 4	375 ± 19
SUMO1₁₀₁	250	−47 ± 6^a	86 ± 5^a	14 ± 4^a	37 ± 4^b	11 ± 4	21 ± 9^b	35 ± 6^b	9 ± 4	63 ± 9^b	3 ± 4	12 ± 6	370 ± 24
SUMO1₉₅	75	−60 ± 5	63 ± 6	6 ± 4	20 ± 3	13 ± 3	73 ± 7	20 ± 3	13 ± 3	249 ± 11	5 ± 4	13 ± 3	372 ± 15
denatured SUMO1₁₀₁	75	−57 ± 5	64 ± 3	5 ± 2	19 ± 4	12 ± 3	70 ± 8	20 ± 5	11 ± 4	240 ± 20	4 ± 4	13 ± 3	378 ± 18
SENP1	250	−65 ± 5^a	51 ± 5^a	1 ± 2^a	3 ± 4^b	13 ± 4	100 ± 18^b	1 ± 4^b	10 ± 2	370 ± 23^b	4 ± 4	13 ± 4	366 ± 21
SENP1-C603S	250	−57 ± 5	64 ± 6	6 ± 3	20 ± 4	13 ± 4	72 ± 14	19 ± 6	9 ± 3	249 ± 17	4 ± 3	13 ± 3	388 ± 21
Δ SENP-SUMO		16 ± 6	33 ± 8	12 ± 4	36 ± 5	0 ± 5	78 ± 20	36 ± 6	0 ± 3	309 ± 24	0 ± 5	0 ± 6	9 ± 28

Neurons (Figs. 1 and 2) and cloned channels in CHO cells (Fig. 4) were studied in whole cell mode using filter and sampling frequencies of 5 and 25 kHz for voltage clamp studies and 1 and 10 kHz for current clamp recording. Voltage-dependent currents were studied after a P/5 leak subtraction. Stimulation protocols are described in the figure legends. Membrane potential and potassium currents were studied in solution A (in mM): 1.3 CaCl₂, 0.5 MgCl₂, 0.4 MgSO₄, 3.56 KCl, 0.44 KH₂PO₄, 139.7 NaCl, 0.34 Na₂HPO₄, 5.5 glucose, and 10 HEPES, pH 7.4 with NaOH. Electrodes were filled with solution B (in mM): 136 KCl, 1 MgCl₂, 2 K₂ATP, 5 EGTA, and 10 HEPES, pH 7.2 with KOH. Sodium currents were studied with solution C in the bath (in mM): 130 NaCl, 5 CsCl, 2 CaCl₂, 1.2 MgCl₂, 5 glucose, and 10 HEPES, pH 7.4 with NaOH. The electrode solution D contained (in mM): 60 CsCl, 80 CsF, 10 EGTA, 1 CaCl₂, 1 MgCl₂, 5 Na₂ATP, and 10 HEPES, pH 7.4 with CsOH. To determine V_1/2, voltage evoking half-maximal conductance, and V_s, the slope of the curve, the normalized current was plotted against voltage and fitted to the Boltzmann equation, G = G_max /(1+exp [−(V−V_1/2)/V_s]), where G_max is maximum conductance. I_PEAK was determined at +50 mV. 8–20 cells were studied in each condition. ΔSENP-SUMO is the mean difference between exposure to SENP1 and 75 pM SUMO1₁₀₁. Vm, resting membrane potential; Rin, input resistance; Ff, firing frequency.

Statistical difference determined by comparison to untreated cells using unpaired t tests, P < 0.01.

Statistical difference determined by comparison to untreated cells using unpaired t tests, P < 0.001.

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