2005 Fiscal Year Final Research Report Summary
Voltage- and K ion-dependent gating of inwardly rectifying K channels
| Project/Area Number |
15390067
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
General physiology
|
|---|
| Research Institution | Kansai Medical University |
|---|
Principal Investigator |
MATSUDA Hiroko Kansai Medical University, Faculty of Medicine, Professor, 医学部, 教授 (10181736)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
TAKETO Megumi Kansai Medical University, Faculty of Medicine, Assistant, 医学部, 助手 (50298189)
HAYASHI Mikio Kansai Medical University, Faculty of Medicine, Assistant, 医学部, 助手 (10368251)
|
|---|
| Project Period (FY) |
2003 – 2005
|
| Keywords | Inwardly rectifying K^+ channel / K ion |
|---|
| Research Abstract |
To know the significance of the negative charges in the extracellular loop of the inwardly rectifying K^+ (Kir2.1) channels, single point mutants (D112N, D114N, D152N and E153Q) and double points mutants (D112N/D114N and D152N/E153Q) were constructed and transfected into COS-1 and HEK-293 cells. Single-channel currents similar to those through wild-type Kir2.1 channels were recorded from cells transfected with each single point mutant and D112N/D114N. Cells transfected with D152N/E153Q did not show inwardly rectifying K^+ currents, although fluorescence images confirmed that channel proteins produced by D152N/E153Q were transported to the cell surface. Tandem tetramers with one E153Q subunit and three double mutant subunits, E153Q-(D152N/E153Q)3, expressed Kir2.1 channels. Tandem tetramers with one D152N subunit and three double mutant subunits, D152N-(D152N/E153Q)3, did not express Kir2.1 channels but those with two D152N subunits and two double mutant subunits, (D152N)2-(D152N/E153Q)2, expressed Kir2.1 channels. In addition, outward currents through wild-type and D172N/E224S channels were recorded from outside-out macropatches in the absence of external K^+. These results suggest that one negative charge of D152 or two negative charges of E153 and K^+ either in the external solution or coming from the inside of cells are required for Kir2.1 channels to function. These negative charges may be involved in stabilizing a half hydrated K^+ ion near the external entrance to the selectivity filter revealed by the structural study of the KcsA K^+ channel.
|
Research Products
(4 results)
