Postulated role of interdomain interaction within the ryanodine receptor in Ca(2+) channel regulation

• Published in: The Journal of biological chemistry 2000-04, Vol.275 (16), p.11618
• Main Authors: Yamamoto, T, El-Hayek, R, Ikemoto, N
• Format: Article
• Language: English
• Subjects: Amino Acid Substitution; Animals; Arginine - metabolism; Calcium - metabolism; Cystine - metabolism; Microsomes - chemistry; Muscle, Skeletal - chemistry; Mutagenesis, Site-Directed; Myocardium - chemistry; Peptide Fragments - chemistry; Peptide Fragments - genetics; Peptide Fragments - physiology; Polylysine - metabolism; Rabbits; Ryanodine Receptor Calcium Release Channel - genetics; Ryanodine Receptor Calcium Release Channel - physiology; Structure-Activity Relationship; Time Factors
• ISSN: 0021-9258
• DOI: 10.1074/jbc.275.16.11618

Localized distribution of malignant hyperthermia (MH) and central core disease (CCD) mutations in N-terminal and central domains of the ryanodine receptor suggests that the interaction between these domains may be involved in Ca(2+) channel regulation. To test this hypothesis, we investigated the effects of a new synthetic domain peptide DP4 corresponding to the Leu(2442)-Pro(2477) region of the central domain. DP4 enhanced ryanodine binding and induced a rapid Ca(2+) release. The concentration for half-maximal activation by agonists was considerably reduced in the presence of DP4. These effects of DP4 are analogous to the functional modifications of the ryanodine receptor caused by MH/CCD mutations (viz. hyperactivation of the channel and hypersensitization of the channel to agonists). Replacement of Arg of DP4 with Cys, mimicking the in vivo Arg(2458)-to-Cys(2458) mutation, abolished the activating effects of DP4. An N-terminal domain peptide DP1 (El-Hayek, R., Saiki, Y., Yamamoto, T., and Ikemoto, N. (1999) J. Biol. Chem. 274, 33341-33347) shows similar activation/sensitization effects. The addition of both DP4 and DP1 produced mutual interference of their activating functions. We tentatively propose that contact between the two (N-terminal and central) domains closes the channel, whereas removal of the contact by these domain peptides or by MH/CCD mutations de-blocks the channel, resulting in hyperactivation/hyper-sensitization effects.