Sites of proteolytic processing and noncovalent association of the distal C-terminal domain of CaV 1.1 channels in skeletal muscle

Joanne T. Hulme, Keiichi Konoki, Teddy W.C. Lin, Marina A. Gritsenko, David G. Camp, Diana J. Bigelow, William A. Catterall

Research output: Contribution to journalArticlepeer-review

83 Citations (Scopus)


In skeletal muscle cells, voltage-dependent potentiation of Ca2+ channel activity requires phosphorylation by cAMP-dependent protein kinase (PKA) anchored via an A-kinase anchoring protein (AKAP15), and the most rapid sites of phosphorylation are located in the C-terminal domain. Surprisingly, the site of interaction of the complex of PKA and AKAP15 with the α1-subunit of CaV1.1 channels lies in the distal C terminus, which is cleaved from the remainder of the channel by in vivo proteolytic processing. Here we report that the distal C terminus is noncovalently associated with the remainder of the channel via an interaction with a site in the proximal C-terminal domain when expressed as a separate protein in mammalian nonmuscle cells. Deletion mapping of the C terminus of the α1-subunit using the yeast two-hybrid assay revealed that a distal C-terminal peptide containing amino acids 1802-1841 specifically interacts with a region in the proximal C terminus containing amino acid residues 1556-1612. Analysis of the purified α1-subunit of CaV1-1 channels from skeletal muscle by saturation sequencing of the intracellular peptides by tandem mass spectrometry identified the site of proteolytic processing as alanine 1664. Our results support the conclusion that a noncovalently associated complex of the α1-subunit truncated at A1664 with the proteolytically cleaved distal C-terminal domain, AKAP15, and PKA is the primary physiological form of CaV1-1 channels in skeletal muscle cells.

Original languageEnglish
Pages (from-to)5274-5279
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number14
Publication statusPublished - 2005 Apr 5
Externally publishedYes


  • Calcium channels
  • Contraction coupling
  • Excitation
  • Protein kinase
  • Proteolysis

ASJC Scopus subject areas

  • General


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