title: Glycosylation and cell surface expression of Kv1.2 potassium channel are regulated by determinants in the pore region.
abstract: Voltage-gated K(+) channels contain six membrane spanning segments and a pore-forming domain. We used site-directed mutation to examine the role of specific amino acids in the extracellular region of the pore in Kv1.2. When expressed in CHO cells, a K(+) current was not observed for mutants S356A, S360A, T383A and T384A. However, coexpression of the Kvbeta2 subunit and the S360A mutant resulted in a robust peak current. Immunocytochemistry for Kv1.2 showed staining throughout the cytoplasm in cells coexpressing the beta2 and S360A, whereas only the perinuclear region was stained in cells expressing the S360A mutant. Western blotting revealed that the major immunoreactive protein in wild-type- and mutant-expressing cells is 60-kDa, but 87-kDa bands were also detected in cells expressing wild-type Kv1.2 and cells coexpressing beta2and S360A. These results suggest that amino acids in the pore region help regulate ion permeability or cellular trafficking by affecting glycosylation of Kv1.2.
authors.affiliation: Department of Pharmacotherapeutics, Showa Pharmaceutical University, Tokyo, Machida, Japan.
authors.forename: Tetsuhiro
authors.initials: T
authors.lastname: Fujita
authors.forename: Iku
authors.initials: I
authors.lastname: Utsunomiya
authors.forename: Jin
authors.initials: J
authors.lastname: Ren
authors.forename: Yousuke
authors.initials: Y
authors.lastname: Matsushita
authors.forename: Miwa
authors.initials: M
authors.lastname: Kawai
authors.forename: Sachie
authors.initials: S
authors.lastname: Sasaki
authors.forename: Keiko
authors.initials: K
authors.lastname: Hoshi
authors.forename: Tadashi
authors.initials: T
authors.lastname: Miyatake
authors.forename: Kyoji
authors.initials: K
authors.lastname: Taguchi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols; D002477:Cells; D006224:Cricetinae; D003412:Cricetulus; D003520:Cyclophosphamide; D004317:Doxorubicin; D006031:Glycosylation; D051663:Kv1.2 Potassium Channel / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D051381:Rats; D014750:Vincristine
chemical_list: D051663:Kv1.2 Potassium Channel; D021122:Protein Subunits; D014750:Vincristine; D004317:Doxorubicin; D003520:Cyclophosphamide; D011188:Potassium