title: Essential, completely conserved glycine residue in the domain III S2-S3 linker of voltage-gated calcium channel alpha1 subunits in yeast and mammals.
abstract: Voltage-gated Ca2+ channels (VGCCs) mediate the influx of Ca2+ that regulates many cellular events, and mutations in VGCC genes cause serious hereditary diseases in mammals. The yeast Saccharomyces cerevisiae has only one gene encoding the putative pore-forming alpha1 subunit of VGCC, CCH1. Here, we identify a cch1 allele producing a completely nonfunctional Cch1 protein with a Gly1265 to Glu substitution present in the domain III S2-S3 cytoplasmic linker. Comparison of amino acid sequences of this linker among 58 VGCC alpha1 subunits from 17 species reveals that a Gly residue whose position corresponds to that of the Cch1 Gly1265 is completely conserved from yeasts to humans. Systematic amino acid substitution analysis using 10 amino acids with different chemical and structural properties indicates that the Gly1265 is essential for Cch1 function because of the smallest residue volume. Replacement of the Gly959 residue of a rat brain Cav1.2 alpha1 subunit (rbCII), positionally corresponding to the yeast Cch1 Gly1265, with Glu, Ser, Lys, or Ala results in the loss of Ba2+ currents, as revealed by the patch clamp method. These results suggest that the Gly residue in the domain III S2-S3 linker is functionally indispensable from yeasts to mammals. Because the Gly residue has never been studied in any VGCC, these findings provide new insights into the structure-function relationships of VGCCs.
authors.affiliation: Biomembrane Signaling Project 2, Tokyo Metropolitan Institute of Medical Science, 3-18-22 Honkomagome, Bunkyo-ku, Tokyo 113-8613, Japan.
authors.forename: Kazuko
authors.initials: K
authors.lastname: Iida
authors.forename: Jinfeng
authors.initials: J
authors.lastname: Teng
authors.forename: Tomoko
authors.initials: T
authors.lastname: Tada
authors.forename: Ayaka
authors.initials: A
authors.lastname: Saka
authors.forename: Masumi
authors.initials: M
authors.lastname: Tamai
authors.forename: Hiroko
authors.initials: H
authors.lastname: Izumi-Nakaseko
authors.forename: Satomi
authors.initials: S
authors.lastname: Adachi-Akahane
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Iida
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D001464:Barium / Q000378:metabolism; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism*; D020746:Calcium Channels, L-Type / Q000235:genetics / Q000378:metabolism*; D030342:Genetic Diseases, Inborn / Q000235:genetics / Q000378:metabolism; D005998:Glycine / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D018408:Patch-Clamp Techniques; D017433:Protein Structure, Secondary / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D051381:Rats; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: C108765:CCH1 protein, S cerevisiae; D015220:Calcium Channels; D020746:Calcium Channels, L-Type; C419385:L-type calcium channel alpha(1C); D029701:Saccharomyces cerevisiae Proteins; D001464:Barium; D005998:Glycine