This data was extracted from Medline abstracts and full texts (when available) in an automated manner.
The table below describes different point mutations at a given position and provides links to other documents. The sentence(s) where the point mutations in KAT1_ARATH at position 118 were found are listed after the table.
Reference #1 (Tang XD et al.): H118A
- Normalized representative currents through H118H , H118N , and H118A recorded at -180 mV and pH i = 7.2 are compared in Fig. 7 A
- The H118A and H118N T A was still dependent on pH i but to a lesser extent
- The results suggest that additional mechanisms may control the pH i dependence of T A because H118A and H118N exhibited smaller and shallower but still noticeable pH i dependence
- (image) View larger version (23K): [in this window] [in a new window] FIGURE 7 Activation time course of H118A and H118N
- (A) Comparison of T A of H118H , H118A , and H118N
- Scaled representative current traces for H118H , H118A , and H118N recorded at pH i = 7.2
- Box plots of t 0.5 for H118H , H118A , and H118N (right)
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Reference #1 (Tang XD et al.): H118D
- Normalized representative currents recorded from the wild type KAT1 (this channel will be referred to as H118H) , H118K , H118R , H118D , and H118E channels at pH i = 7.2 in response to voltage pulses to -180 mV are shown in Fig. 5 A
- The negatively charged amino acid mutants , H118D and H118E , were noticeably slower in their activation kinetics than the H118H channel but again very similar to each other
- Normalized representative tail currents of H118K , H118D , and H118N recorded at +60 mV are compared in Fig. 8 A , and they were indistinguishable
- (A) Representative tail currents from H118N , H118D , and H118K
- Representative macroscopic currents from H118H , H118R , and H118D elicited at various voltages and their macroscopic G(V) curves are shown in Fig. 9
- 5 and 8 C , T A of H118D is markedly slower
- The small shift in G(V) found for the H118D mutant may be caused by hyperpolarizing pulses that were not sufficiently long enough for the channel activation to reach the steady state
- (A) Macroscopic current families from H118H , H118R , and H118D
- The currents were recorded in response to 5-s V P from -60 to -180 mV in 10-mV increments and then switched to +70 mV (H118H and H118D)
- Representative single-channel openings of H118H and H118D are shown in Fig. 10 A
- This is illustrated by the first latency distributions of H118H and H118D in Fig. 10 B
- Consistent with the macroscopic current results presented earlier , the first latency distribution of H118D at -160 mV was markedly slower than that of H118H
- The average median first latencies for H118H and H118D were 96 ± 17 ms (n = 4) and 410 ± 47 ms (n = 4) , respectively
- The open and closed duration histograms were constructed from representative single-channel currents recorded at -160 mV from H118H and H118D (Fig. 11 )
- The mean open durations were 15.2 ± 1.5 ms (n = 5) and 15.3 ± 1.6 ms (n = 5) , and the mean closed durations were 3.1 ± 0.3 (n = 5) ms and 3.1 ± 0.2 ms (n = 5) for H118H and H118D , respectively
- (A) Representative single-channel currents for H118H and H118D that were elicited by a 60-s hyperpolarizing pulse to -160 mV from 0 mV , pH i = 7.2
- Note the prolonged first latency of the H118D channel
- (B) Comparison of the first latency distributions for H118H and H118D
- To construct the first latency distributions for H118H and H118D , 56 and 78 hyperpolarization epochs were used respectively
- (C) Comparison of the p o(V) relations for H118H , H118D , and H118K
- (image) View larger version (30K): [in this window] [in a new window] FIGURE 11 Comparison of the open and closed time durations for H118H and H118D
- (B) Open and closed durations of the currents recorded from a single H118D channel
- Single-channel current amplitudes are not affected by the H118 mutations Although the first latencies are affected by the charged H118 mutations , the single-channel amplitudes of the H118 mutants (H118D , H118E , H118K , and H118R) were very similar to that of the wild type KAT1 channel
- This finding can be seen in the representative single-channel currents recorded from H118H and H118D shown in Fig. 10 A
- To determine whether the total global charge near the amino acid residue 118 is important in determining the activation kinetics , we constructed the H118Rx3 and H118Dx3 mutants , where histidine-118 was replaced with three arginine or aspartate residues , respectively
- (A) Macroscopic H118H and H118D currents simulated by Scheme 4
- (B) Single-channel H118H and H118D currents simulated by Scheme 4
- The first latency events for the H118D channel are even longer (lower panel ; also see Fig. 10 A for the latency difference between the recorded H118H and H118D currents)
- However , after the channel opens , the steady-state single-channel kinetics is similar in H118H and H118D
- Specifically , to describe the effects of H118D mutation in the voltage range of -130 to -200 mV , k 01(0) was decreased by ~65% , from 0.57 to 0.2 s -1 (n = 3) , without changing its equivalent charge
- The measured and simulated macroscopic currents for the wild type and H118D channels at -180 and -150 mV are compared in Fig. 14 A
- Manipulations of the rate constants among C4 , C3 , and C0 were not able to simulate the H118D's effect , because changes in the values of k 03 , k30 , k34 , and k43 compromised the sigmoidal characteristic of the activation kinetics (data not shown)
- Manipulations in the two rate constants involved in the single-channel burst behavior , k25 and k52 , did not simulate the effect of the H118D mutations , consistent with the observation that the burst behavior was not altered in the H118D mutations (Figs
- Representative KAT1 wild type and H118D single-channel currents at -180 mV simulated using Scheme 4 are shown in Fig. 14 B
- The simulated data well match the measured results , including some prolonged first latency events in H118D
- KST1 has a glutamate at the H118-equivalent position , and its T A is similar to that of KAT1 H118E or H118D
- More importantly , it is enhanced in the H118D (Figs
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Reference #1 (Tang XD et al.): H118E
- Normalized representative currents recorded from the wild type KAT1 (this channel will be referred to as H118H) , H118K , H118R , H118D , and H118E channels at pH i = 7.2 in response to voltage pulses to -180 mV are shown in Fig. 5 A
- The negatively charged amino acid mutants , H118D and H118E , were noticeably slower in their activation kinetics than the H118H channel but again very similar to each other
- (B) Henderson-Hasselbalch plot of the normalized t 0.5-pH i relations for the H118E and H118K mutants
- For H118K and H118E , the t 0.5max and t 0.5min values of wild type KAT1 were used because it was difficult to determine the extreme values for these mutant channels
- Within the pH i range of 5.2 to 8.2 , where H118H is very pH i sensitive (see Fig. 2 ) , neither H118E nor H118K showed any marked pH i dependence
- Activation time course of H118E remained slow and mostly independent of pH i and that of H118K remained fast and also independent of pH i in this pH range (Fig. 5 B)
- At the extreme pH i values , however , both H118E and H118K exhibited some pH i dependence
- For example , H118E T A was noticeably and consistently faster at pH i = 4.2 than that at pH i = 5.2 , and H118K T A was slower at pH i = 10.2 than at 8.2 (Fig. 5 B)
- Because t 0.5min for H118E and t 0.5max for H118K could not be obtained , the pH i dependence data were not confidently fitted with the Henderson-Hasselbalch formulation
- However , using pK values of 4.3 and 10.8 , which are often described for the side chains of E and K (Edsall and Wyman , 1958(image) ) , the small pH i dependence of H118E and H118K could be approximated (Fig. 5 B)
- It is also possible that structural determinants other than the amino acid at position 118 are involved in regulating the small pH i sensitivities of the H118E and H118K mutant channels
- The results that T A of H118E is slower and less pH i-dependent than that of H118H predict that T A of KST1 with E at the H118-equivalent position should be slower than that of H118H and similar to that of H118E
- Normalized representative currents through H118H , H118E , and KST1 measured at pH i = 7.2 are compared in Fig. 6 A
- Consistent with the prediction , T A of KST1 was slower than that of H118H and indistinguishable from that of H118E (Fig. 6 A ; also see Fig. 5 of Hedrich and Dietrich , 1996(image) )
- Furthermore , the activation time course of KST1 was much less dependent on pH i than that of H118H but very similar to that of H118E
- At extreme lower pH i , as found with H118E , KST1 T A accelerated (Fig. 6 B)
- (image) View larger version (17K): [in this window] [in a new window] FIGURE 6 Activation time course of H118H , H118E , and KST1
- (A) Scaled representative currents for H118H , H118E , and KST1 elicited at -180 mV , pH i = 7.2
- Single-channel current amplitudes are not affected by the H118 mutations Although the first latencies are affected by the charged H118 mutations , the single-channel amplitudes of the H118 mutants (H118D , H118E , H118K , and H118R) were very similar to that of the wild type KAT1 channel
- The macroscopic currents of H118H and H118E were recorded in the solutions of different ionic strength
- However , T A of both H118H and H118E at pH i = 6.2 where H118 is expected to be protonated , was not markedly affected by the changes in the internal solution ionic strength (data not shown)
- KST1 has a glutamate at the H118-equivalent position , and its T A is similar to that of KAT1 H118E or H118D
- 5 and 14 ) and H118E channels (Fig. 5 )
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Reference #1 (Tang XD et al.): H118K
- Normalized representative currents recorded from the wild type KAT1 (this channel will be referred to as H118H) , H118K , H118R , H118D , and H118E channels at pH i = 7.2 in response to voltage pulses to -180 mV are shown in Fig. 5 A
- The H118K and H118R channels with a positively charged amino acid at position 118 activated markedly faster than the H118H channel at pH i = 7.2
- However , T A of H118K and H118R , with two very different side chain structures (Richardson and Richardson , 1989(image) ) but the same positive charge , were virtually indistinguishable
- (B) Henderson-Hasselbalch plot of the normalized t 0.5-pH i relations for the H118E and H118K mutants
- For H118K and H118E , the t 0.5max and t 0.5min values of wild type KAT1 were used because it was difficult to determine the extreme values for these mutant channels
- Within the pH i range of 5.2 to 8.2 , where H118H is very pH i sensitive (see Fig. 2 ) , neither H118E nor H118K showed any marked pH i dependence
- Activation time course of H118E remained slow and mostly independent of pH i and that of H118K remained fast and also independent of pH i in this pH range (Fig. 5 B)
- At the extreme pH i values , however , both H118E and H118K exhibited some pH i dependence
- For example , H118E T A was noticeably and consistently faster at pH i = 4.2 than that at pH i = 5.2 , and H118K T A was slower at pH i = 10.2 than at 8.2 (Fig. 5 B)
- Because t 0.5min for H118E and t 0.5max for H118K could not be obtained , the pH i dependence data were not confidently fitted with the Henderson-Hasselbalch formulation
- However , using pK values of 4.3 and 10.8 , which are often described for the side chains of E and K (Edsall and Wyman , 1958(image) ) , the small pH i dependence of H118E and H118K could be approximated (Fig. 5 B)
- It is also possible that structural determinants other than the amino acid at position 118 are involved in regulating the small pH i sensitivities of the H118E and H118K mutant channels
- Normalized representative tail currents of H118K , H118D , and H118N recorded at +60 mV are compared in Fig. 8 A , and they were indistinguishable
- (A) Representative tail currents from H118N , H118D , and H118K
- (C) Comparison of the p o(V) relations for H118H , H118D , and H118K
- Single-channel current amplitudes are not affected by the H118 mutations Although the first latencies are affected by the charged H118 mutations , the single-channel amplitudes of the H118 mutants (H118D , H118E , H118K , and H118R) were very similar to that of the wild type KAT1 channel
- We also found that the accelerated activation time course in the H118K channel could also be simulated by increasing the value of k 01(0) by ~190% without a change in its voltage dependence (n = 3 , data not shown)
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Reference #1 (Tang XD et al.): H118N
- Normalized representative currents through H118H , H118N , and H118A recorded at -180 mV and pH i = 7.2 are compared in Fig. 7 A
- The H118A and H118N T A was still dependent on pH i but to a lesser extent
- However , the same pH i change induced only about a 2-fold change in H118N t 0.5 (Fig. 7 B)
- More noticeably , the t 0.5-pH i relation of H118N was much less steeper than that of H118H and the normalized pH i dependence could no longer be well described by a simple Henderson-Hasselbalch formulation (Fig. 7 B , right)
- The results suggest that additional mechanisms may control the pH i dependence of T A because H118A and H118N exhibited smaller and shallower but still noticeable pH i dependence
- (image) View larger version (23K): [in this window] [in a new window] FIGURE 7 Activation time course of H118A and H118N
- (A) Comparison of T A of H118H , H118A , and H118N
- Scaled representative current traces for H118H , H118A , and H118N recorded at pH i = 7.2
- Box plots of t 0.5 for H118H , H118A , and H118N (right)
- (B) Effects of pH i on the H118N mutant
- Normalized t 0.5-pH i relation for the H118N channel (right)
- Normalized representative tail currents of H118K , H118D , and H118N recorded at +60 mV are compared in Fig. 8 A , and they were indistinguishable
- (A) Representative tail currents from H118N , H118D , and H118K
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Reference #1 (Tang XD et al.): H118R
- Normalized representative currents recorded from the wild type KAT1 (this channel will be referred to as H118H) , H118K , H118R , H118D , and H118E channels at pH i = 7.2 in response to voltage pulses to -180 mV are shown in Fig. 5 A
- The H118K and H118R channels with a positively charged amino acid at position 118 activated markedly faster than the H118H channel at pH i = 7.2
- However , T A of H118K and H118R , with two very different side chain structures (Richardson and Richardson , 1989(image) ) but the same positive charge , were virtually indistinguishable
- Representative macroscopic currents from H118H , H118R , and H118D elicited at various voltages and their macroscopic G(V) curves are shown in Fig. 9
- (A) Macroscopic current families from H118H , H118R , and H118D
- For H118R , the currents were recorded in response to 4-s V P from -60 to -180 mV in 10-mV increments and then to -50 mV
- Single-channel current amplitudes are not affected by the H118 mutations Although the first latencies are affected by the charged H118 mutations , the single-channel amplitudes of the H118 mutants (H118D , H118E , H118K , and H118R) were very similar to that of the wild type KAT1 channel
- To determine whether the total global charge near the amino acid residue 118 is important in determining the activation kinetics , we constructed the H118Rx3 and H118Dx3 mutants , where histidine-118 was replaced with three arginine or aspartate residues , respectively
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2005, KChannelDB.
cmbi.ru.nl), 17-Aug-2005