Identification of the protein regions mediating the assembly of rat ether-??go-go potassium channels

• Main Authors: I-HSIU CHEN, 陳怡秀
• Other Authors: Chung-Jiuan Jeng
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/78280746178026824431

碩士 === 國立陽明大學 === 解剖學及細胞生物學研究所 === 98 === Functional voltage-gated potassium channels (Kv) contain four pore-forming α-subunits, as well as auxiliary subunits. Each α-subunit comprises six membrane-spanning regions, S1 to S6, with a P (pore) region between S5 and S6. Both the N- and C-terminal regions are located at the intracellular side. The assembly of α-subunits into tetramers is a prerequisite for producing functional potassium channels. Different types of K+ channel subunit assembly domain have been identified. In shaker-related (Kv1) channels, for example, the cytoplasmic amino-terminal tetramerization (T1) domain has been shown to be crucial for channel assembly. In contrast, ether-a-go-go (EAG) K+ channels have been proposed to assemble via a short carboxyl assembly domain (CAD) in the cytoplasmic C terminus. The main purpose of this study is to re-examine the role of the CAD in the assembly of EAG channels. Our electrophysiological study shows that EAG channels may form functional channels in the absence of CAD, suggesting that CAD is not the only determinant for channel assembly. Co-immunoprecipitation indicates that the different degrees of the rEag1 C-terminal deletion mutants are able to associate with the wild-type rEag1 (WT-rEag1), suggesting that the transmembrane regions of rEag1 proteins also contribute to the inter-subunit interaction. Immunofluorescent staining, surface biotinylation, and glyconase analysis further suggest that rEag1 C-terminal deletion affects surface delivery, ER export, and protein glycosylation.