KChannelDB: Extraction of mutation data from the literature

2005, KChannelDB.

This data was extracted from Medline abstracts and full texts (when available) in an automated manner.

The table below describes the selected point mutation and provides links to other documents. The sentence(s) where the point mutation H118K was found are listed after the table.

The mutated residues are also indicated in the family sequence alignments and hyperlinked to the corresponding mutation pages.

Point mutation H118K in KAT1_ARATH

Point mutation:	H118K
Domain:	Loop 2-3
General numbering (KChannelDB):	-
Protein:	KAT1_ARATH (KAT1,At5g46240,MPL12.)	Swiss-Prot Cross-reference table Family page
Other point mutations / same protein / same position	Point mutations at position 118 in KAT1_ARATH
Other point mutations / same protein	List of mutations in KAT1_ARATH
Family alignments	AKT-like Inward rectifiers 6TMs Plant potassium channels
Other point mutations / same position	Position 122 in AKT-like Inward rectifiers 6TMs family Position 122 in Plant potassium channels family
Reference:	Histidine(118) in the S2-S3 linker specifically controls activation of the KAT1 channel expressed in Xenopus oocytes. Tang XD, Marten I, Dietrich P, Ivashikina N, Hedrich R, Hoshi T Biophys J 2000 Mar;78(3):1255-69.	Medline
Other point mutations / same article	List
Text source	HTML full text
Validation status	Not yet checked

Relevant sentences:

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)

F.Horn (kchanneldbcmbi.ru.nl), 17-Aug-2005