Transfer of 1,4-dihydropyridine sensitivity from L-type to class A (BI) calcium channels.
L-type Ca2+ channels are characterized by their unique sensitivity to organic Ca2+ channel modulators like the 1,4-dihydropyridines (DHPs). To identify molecular motifs mediating DHP sensitivity, we transferred this sensitivity from L-type Ca2+ channels to the DHP-insensitive class A brain Ca2+ channel, BI-2. Expression of chimeras revealed minimum sequence stretches conferring DHP sensitivity including segments IIIS5, IIIS6, and the connecting linker, as well as the IVS5-IVS6 linker plus segment IVS6. DHP agonist and antagonist effects are determined by different regions within the repeat IV motif. Sequence regions responsible for DHP sensitivity comprise only 9.4% of the overall primary structure of a DHP-sensitive alpha 1A/alpha 1S construct. This chimera fully exhibits the DHP sensitivity of channels formed by L-type alpha 1 subunits. In addition, it displays the electrophysiological properties of alpha 1A, as well as its sensitivity toward the peptide toxins omega-agatoxin IVA and omega-conotoxin MVIIC.
Grabner
M
M
Institut für Biochemische Pharmakologie, Universität Innsbruck, Austria.
Wang
Z
Z
Hering
S
S
Striessnig
J
J
Glossmann
H
H
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism*; D002120:Calcium Channel Agonists / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000737:chemistry* / Q000187:drug effects* / Q000235:genetics; D020746:Calcium Channels, L-Type; D002347:Carps; D004095:Dihydropyridines / Q000494:pharmacology*; D015640:Ion Channel Gating / Q000187:drug effects; D017275:Isradipine / Q000494:pharmacology; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D010455:Peptides / Q000494:pharmacology; D017434:Protein Structure, Tertiary; D011758:Pyrroles / Q000494:pharmacology; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000187:drug effects*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013111:Spider Venoms / Q000494:pharmacology; D020867:omega-Agatoxin IVA; D020960:omega-Conotoxins
D002120:Calcium Channel Agonists; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D004095:Dihydropyridines; D010446:Peptide Fragments; D010455:Peptides; D011758:Pyrroles; D011993:Recombinant Fusion Proteins; D013111:Spider Venoms; D020867:omega-Agatoxin IVA; D020960:omega-Conotoxins; C071658:FPL 64176; C075851:omega-conotoxin-MVIIC; C038806:1,4-dihydropyridine; D002118:Calcium; D017275:Isradipine