Azidobutyryl clentiazem, a new photoactivatable diltiazem analog, labels benzothiazepine binding sites in the α1 subunit of the skeletal muscle calcium channel

Toshiro Watanabe, Huba Kalasz, Hideo Yabana, Akihiko Kuniyasu, John Mershon, Kiyoshi Itagaki, Pal L. Vaghy, Kazuaki Naito, Hitoshi Nakayama, Arnold Schwartz

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36 Citations (Scopus)


[3H]Azidobutyryl clentiazem, a new photoactivatable diltiazem derivative, has a higher binding affinity than azidobutyryl diltiazem. It can be covalently incorporated into the α1 subunit of the skeletal muscle calcium channel by UV irradiation, which allows the benzothiazepine binding site to be determined. The photolabeled α1 subunit and its proteolytic fragments were analyzed with a panel of sequence-directed antibodies. The results suggest that the linker region between segment S5 and S6 of domain IV is involved in benzothiazepine binding. This site is different from the dihydropyridine and verapamil binding sites.

Original languageEnglish
Pages (from-to)261-264
Number of pages4
JournalFEBS letters
Issue number3
Publication statusPublished - Nov 22 1993



  • Calcium channel
  • Diltiazem-binding site
  • Photoaffinity labeling
  • Sequence-directed antibody
  • [H]Azidobutyryl clentiazem

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology

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