The molecular chaperone hsp70 interacts with the cytosolic II-III loop of the Cav2.3 E-type voltage-gated Ca2+ channel.
Multiple types of voltage-activated Ca2+ channels (T, L, N, P, Q, R type) coexist in excitable cells and participate in synaptic differentiation, secretion, transmitter release, and neuronal plasticity. Ca2+ ions entering cells trigger these events through their interaction with the ion channel itself or through Ca2+ binding to target proteins initiating signalling cascades at cytosolic loops of the ion conducting subunit (Cava1). These loops interact with target proteins in a Ca2+-dependent or independent manner. In Cav2.3-containing channels the cytosolic linker between domains II and III confers a novel Ca2+ sensitivity to E-type Ca2+ channels including phorbol ester sensitive signalling via protein kinase C (PKC) in Cav2.3 transfected HEK-293 cells. To understand Ca2+ and phorbol ester mediated activation of Cav2.3 Ca2+ channels, protein interaction partners of the II-III loop were identified. FLAG-tagged II-III - loop of human Cav2.3 was over-expressed in HEK 293 cells, and the molecular chaperone hsp70, which is known to interact with PKC, was identified as a novel functional interaction partner. Immunopurified II-III loop-protein of neuronal and endocrine Cav2.3 splice variants stimulate autophosphorylation of PKCa, leading to the suggestion that hsp70--binding to the II-III loop--may act as an adaptor for Ca2+ dependent targeting of PKC to E-type Ca2+ channels.
Institute for Neurophysiology, University of Cologne, Germany.
Andreas
A
Krieger
Kayalvizhi
K
Radhakrishnan
Alexey
A
Pereverzev
Siarhei A
SA
Siapich
Mohammed
M
Banat
Marcel A
MA
Kamp
Jérome
J
Leroy
Udo
U
Klöckner
Jürgen
J
Hescheler
Marco
M
Weiergräber
Toni
T
Schneider
D000595:Amino Acid Sequence; D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000737:chemistry* / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D002417:Cattle; D002460:Cell Line; D003600:Cytosol / Q000378:metabolism*; D006146:Guanidines / Q000494:pharmacology; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects; D007700:Kinetics; D007785:Lactose / Q000494:pharmacology; D013058:Mass Spectrometry; D008954:Models, Biological; D008969:Molecular Sequence Data; D018408:Patch-Clamp Techniques; D010477:Perfusion; D010766:Phosphorylation; D011233:Precipitin Tests; D051571:Protein Kinase C-alpha / Q000378:metabolism; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D012160:Retina / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D000903:Antibiotics, Antineoplastic; D015220:Calcium Channels; D006146:Guanidines; D018840:HSP70 Heat-Shock Proteins; D021122:Protein Subunits; D051571:Protein Kinase C-alpha; D007785:Lactose; D002118:Calcium; C037258:gusperimus