title: Mutations and deletions within the S8-S9 interdomain region abolish complementation of N- and C-terminal domains of Ca(2+)-activated K+ (BK) channels.
abstract: A full length alpha-subunit of the Ca(2+)-activated K+ (BK) channel with an inactivating mutation in the C-terminus can complement a functional C-terminal fragment. We analyzed deletions and amino acid changes within the S8-S9 interdomain region for their ability to allow complementation. Cys612 and His616 that are located in a region that contains two overlapping signature sequences, a immunoglobulin signature sequence and a heme binding domain, are essential for a functional channel. These two amino acid residues are also essential for complementation. The deletion of the PEST sequence does not affect the function of the BK channel; however, without the PEST sequence, complementation by a functional C-terminal fragments is no longer possible. The ability to complement a functional channel is restricted to the C-terminal fragment and requires that the complete alpha-subunit or the larger N-terminal fragment contains both, the immunoglobulin signature sequence the PEST sequence.
authors.affiliation: Pharmacia & Upjohn, Inc., Kalamazoo, Michigan 49007, USA.
authors.forename: L S
authors.initials: LS
authors.lastname: Wood
authors.forename: G
authors.initials: G
authors.lastname: Vogeli
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001011:Aorta; D002118:Calcium / Q000378:metabolism; D003001:Cloning, Molecular; D017931:DNA Primers; D005816:Genetic Complementation Test; D006418:Heme / Q000378:metabolism; D006801:Humans; D007136:Immunoglobulins / Q000737:chemistry / Q000235:genetics; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D051036:Large-Conductance Calcium-Activated Potassium Channels; D008845:Microinjections; D008969:Molecular Sequence Data; D009154:Mutation; D009865:Oocytes / Q000502:physiology; D018408:Patch-Clamp Techniques; D016133:Polymerase Chain Reaction; D015221:Potassium Channels / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D024681:Potassium Channels, Calcium-Activated; D011487:Protein Conformation; D017384:Sequence Deletion; D014981:Xenopus
chemical_list: D017931:DNA Primers; D007136:Immunoglobulins; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D051036:Large-Conductance Calcium-Activated Potassium Channels; D015221:Potassium Channels; D024681:Potassium Channels, Calcium-Activated; D006418:Heme; D002118:Calcium