| Co-Investigator(Kenkyū-buntansha) |
TANEMOTO Masayuki Osaka University Faculty of Medicine, Assistant Professor, 医学部, 助手 (40303945)
INANOBE Atsuhi Osaka University Faculty of Medicine, Assistant Professor, 医学部, 助手 (00270851)
HORIO Yoshiyuki Osaka University Faculty of Medicine, Associate Professor, 医学部, 助教授 (30181530)
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| Research Abstract |
(1) ATP sensitive potassium channels
A) We cloned a new sulfonylurea receptor(SUR2b) and revealed it forms a smooth muscle type ATP sensitive K+channel with Kir6.1. ATP sensitive K+channel is reported to be regulated by intracellular nucleotides and K+channel openers. We found out that the regulation of the ATP sensitive K+channel is different according to the difference of the channel forming units.
B) We made several chimeras between Kir6.1 and Kir6.2, and by using these chimeras we revealed that the pore-forming region of the channel is responsible for determining channel conductance. Furthermore we found out the amino acids Ser (113), Ile (114), His (115), and Val (138) are major determinant of channel conductance of Kir6.2.
(2) G-protein regulated potassium channels
A) We revealed G-protein regulated K+channel of dopaminergic neurons in substancia nigra (SN) is composed from channel subunits, Kir3.2a and Kir3.2c. We also revealed SAP97, one of the members of anchering proteins which h
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ave PSD domains, is also expressed with these K+ channels.
B) We showed Kir3.1 and Kir3.4 are expressed on the membrane of secretary vesicles in TSH secreting cells of pituitary body. By stimulating these cells with agonists, functional K+channels is expressed on the plasma membrane after fusion of secretary vesicles to the plasma membrane.
C) We cloned a new subunit of G-protein regulated K+channel, Kir3.lb. This clone is a spliced variant of Kir3.la (former reported as Kir3.1). Checking the function of this clone, we showed strong evidence that C-terminal portion of Kir3.1 is indespensable for the channel activation by G-protein.
(3) other potassium channels
A) Kir2.Os are expressed on different cells in olfactory bulb (GB). This cell-specific expression of each channel units might indicate the functional specificity of them in the olfactory sensory system.
B) In CNS, Kir4.1 (Kirl.2) was distributed especially on the basolateral membrane of epithelium of inner lymph follicle, glial cells, and ependymal cells. In retina, it is expressed on Muller cells. These specific distribution of this channel reflects a functional importance of Kir4.1 in handling potassium ions between different ional milieus.
C) We also cloned new four membrane spanning K+channel (CTBAK) from heart cDNA library. Less
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