title: Ca(v)2.3 Ca2+ channel interacts with the G1-subunit of V-ATPase.
abstract: BACKGROUND
  Calcium channels are essential in coupling action potential to signal transduction in cells. There are several types of calcium channels, which can be pharmacologically classified as L-, N-, P/Q-, R- and T-type. But molecular basis of R-type channels is less clearly understood compared the other channel types. Therefore the current study aims at understanding the molecular functions of R-type calcium channels by identifying interaction partners of the channel.
  
  
  METHODS
  In order to do so, a yeast two hybrid (Y2H) screen, with carboxy terminus of α1 subunit of the channel, as the bait, was performed. G1 subunit of v-ATPase was identified as a putative interaction partner of human Ca(v)2.3 by using the Y2H screening. The interaction was confirmed by immunoprecipitation. To study the functional importance of the interaction, bafilomycin A(1), a potent and specific inhibitor of v-ATPase was used in patch-clamp recordings in Ca(v)2.3 stably-transfected HEK-293 cells (2C6) as well as in electroretinography of the isolated bovine retina expressing R-type Ca(2+) channels.
  
  
  RESULTS
  G1 subunit of v-ATPase interacts with C-terminal tail of Ca(v)2.3 and bafilomycin A(1) reduces Ca(v)2.3 mediated calcium currents. Additionally peak I(Ca) is inhibited in retinal signal transduction when recorded as ERG b-wave.
  
  
  CONCLUSIONS
  The results suggest that v-ATPase interacts physically and also functionally with Ca(v)2.3. This is the first demonstration of association of Ca(v)2.3 C-terminus with a protein complex which is involved in transmembrane signalling.
authors.affiliation: Institute of Neurophysiology, Center of Molecular Medicine Cologne, University of Cologne, Robert-Koch-Strasse 39, Cologne, Germany.
authors.forename: Kayalvizhi
authors.initials: K
authors.lastname: Radhakrishnan
authors.forename: Marcel A
authors.initials: MA
authors.lastname: Kamp
authors.forename: Siarhei A
authors.initials: SA
authors.lastname: Siapich
authors.forename: Jürgen
authors.initials: J
authors.lastname: Hescheler
authors.forename: Matthias
authors.initials: M
authors.lastname: Lüke
authors.forename: Toni
authors.initials: T
authors.lastname: Schneider
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020908:Calcium Channels, R-Type / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002417:Cattle; D004596:Electroretinography; D004791:Enzyme Inhibitors / Q000494:pharmacology; D057809:HEK293 Cells; D006801:Humans; D047468:Immunoprecipitation; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology*; D018942:Macrolides / Q000494:pharmacology; D008564:Membrane Potentials / Q000502:physiology; D018408:Patch-Clamp Techniques; D010957:Plasmids; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012160:Retina / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D046509:Tissue Culture Techniques; D014162:Transfection; D020798:Two-Hybrid System Techniques
chemical_list: C423009:CACNA1E protein, human; D020908:Calcium Channels, R-Type; D027682:Cation Transport Proteins; D004791:Enzyme Inhibitors; D018942:Macrolides; D021122:Protein Subunits; D011994:Recombinant Proteins; C040929:bafilomycin A1; D000251:Adenosine Triphosphatases; D002118:Calcium