title: Postulated role of interdomain interaction within the ryanodine receptor in Ca(2+) channel regulation.
abstract: 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.
authors.affiliation: Boston Biomedical Research Institute, Watertown, Massachusetts 02472, USA.
authors.forename: T
authors.initials: T
authors.lastname: Yamamoto
authors.forename: R
authors.initials: R
authors.lastname: El-Hayek
authors.forename: N
authors.initials: N
authors.lastname: Ikemoto
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D001120:Arginine / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D003553:Cystine / Q000378:metabolism; D008861:Microsomes / Q000737:chemistry; D018482:Muscle, Skeletal / Q000737:chemistry; D016297:Mutagenesis, Site-Directed; D009206:Myocardium / Q000737:chemistry; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D011107:Polylysine / Q000378:metabolism; D011817:Rabbits; D019837:Ryanodine Receptor Calcium Release Channel / Q000235:genetics / Q000502:physiology*; D013329:Structure-Activity Relationship; D013997:Time Factors
chemical_list: D010446:Peptide Fragments; D019837:Ryanodine Receptor Calcium Release Channel; D011107:Polylysine; D003553:Cystine; D001120:Arginine; D002118:Calcium