title: The subfamily-specific assembly of Eag and Erg K+ channels is determined by both the amino and the carboxyl recognition domains.
abstract: A functional voltage-gated K(+) (Kv) channel comprises four pore-forming α-subunits, and only members of the same Kv channel subfamily may co-assemble to form heterotetramers. The ether-à-go-go family of Kv channels (KCNH) encompasses three distinct subfamilies: Eag (Kv10), Erg (Kv11), and Elk (Kv12). Members of different ether-à-go-go subfamilies, such as Eag and Erg, fail to form heterotetramers. Although a short stretch of amino acid sequences in the distal C-terminal section has been implicated in subfamily-specific subunit assembly, it remains unclear whether this region serves as the sole and/or principal subfamily recognition domain for Eag and Erg. Here we aim to ascertain the structural basis underlying the subfamily specificity of ether-à-go-go channels by generating various chimeric constructs between rat Eag1 and human Erg subunits. Biochemical and electrophysiological characterizations of the subunit interaction properties of a series of different chimeric and truncation constructs over the C terminus suggested that the putative C-terminal recognition domain is dispensable for subfamily-specific assembly. Further chimeric analyses over the N terminus revealed that the N-terminal region may also harbor a subfamily recognition domain. Importantly, exchanging either the N-terminal or the C-terminal domain alone led to a virtual loss of the intersubfamily assembly boundary. By contrast, simultaneously swapping both recognition domains resulted in a reversal of subfamily specificity. Our observations are consistent with the notion that both the N-terminal and the C-terminal recognition domains are required to sustain the subfamily-specific assembly of rat Eag1 and human Erg.
authors.affiliation: Institute of Anatomy and Cell Biology, School of Medicine, and National Yang-Ming University, No. 155, Section 2, Li-Non Street, Taipei 12212, Taiwan.
authors.forename: Ting-Feng
authors.initials: TF
authors.lastname: Lin
authors.affiliation: Institute of Anatomy and Cell Biology, School of Medicine, and National Yang-Ming University, No. 155, Section 2, Li-Non Street, Taipei 12212, Taiwan.
authors.forename: I-Wen
authors.initials: IW
authors.lastname: Lin
authors.affiliation: Department of Medical Research, National Taiwan University Hospital, Taipei 10051, Taiwan.
authors.forename: Shu-Ching
authors.initials: SC
authors.lastname: Chen
authors.affiliation: Institute of Anatomy and Cell Biology, School of Medicine, and National Yang-Ming University, No. 155, Section 2, Li-Non Street, Taipei 12212, Taiwan.
authors.forename: Hao-Han
authors.initials: HH
authors.lastname: Wu
authors.affiliation: Institute of Anatomy and Cell Biology, School of Medicine, and National Yang-Ming University, No. 155, Section 2, Li-Non Street, Taipei 12212, Taiwan.
authors.forename: Chi-Sheng
authors.initials: CS
authors.lastname: Yang
authors.affiliation: Institute of Anatomy and Cell Biology, School of Medicine, and National Yang-Ming University, No. 155, Section 2, Li-Non Street, Taipei 12212, Taiwan.
authors.forename: Hsin-Yu
authors.initials: HY
authors.lastname: Fang
authors.affiliation: Institute of Anatomy and Cell Biology, School of Medicine, and National Yang-Ming University, No. 155, Section 2, Li-Non Street, Taipei 12212, Taiwan.
authors.forename: Mei-Miao
authors.initials: MM
authors.lastname: Chiu
authors.affiliation: Institute of Anatomy and Cell Biology, School of Medicine, and National Yang-Ming University, No. 155, Section 2, Li-Non Street, Taipei 12212, Taiwan; Brain Research Center, National Yang-Ming University, No. 155, Section 2, Li-Non Street, Taipei 12212, Taiwan and. Electronic address: cjjeng@ym.edu.tw.
authors.forename: Chung-Jiuan
authors.initials: CJ
authors.lastname: Jeng
mesh_terms: D000818:Animals; D051638:Ether-A-Go-Go Potassium Channels / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D051381:Rats; D014982:Xenopus laevis
chemical_list: D051638:Ether-A-Go-Go Potassium Channels; C496886:Kcnh1 protein, rat
keywords: Electrophysiology; Potassium Channel; Protein Assembly; Protein Domain; Site-directed Mutagenesis; Western Blot