title: Both basic and acidic amino acid residues of IpTx(a) are involved in triggering substate of RyR1.
abstract: Imperatoxin A (IpTx(a)) is known to modify the gating of skeletal ryanodine receptor (RyR1). In this paper, the ability of charged aa residues of IpTx(a) to induce substate of native RyR1 in HSR was examined. Our results show that the basic residues (e.g., Lys¹⁹, Lys²⁰, Lys²², Arg²³, and Arg²⁴) are important for producing substate of RyR1. In addition, other basic residues (e.g., Lys³⁰, Arg³¹, and Arg³³ near the C-terminus and some acidic residues (e.g., Glu²⁹, Asp¹³, and Asp²) are also involved in the generation of substate. Residues such as Lys⁸ and Thr²⁶ may be involved in the self-regulation of substate of RyR1, since alanine substitution of the aa residues led to a drastic conversion to the substate. The modifications of the channel gating by the wild-type and mutant toxins were similar in purified RyR1. Taken together, the specific charge distributions on the surface of IpTx(a) are essential for regulation of the channel gating of RyR1.
authors: Systems Biology Research Center, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712, Republic of Korea.
authors: In Ra
authors: IR
authors: Seo
authors: Dae Eun
authors: DE
authors: Kang
authors: Dong Woo
authors: DW
authors: Song
authors: Do Han
authors: DH
authors: Kim
mesh_terms: D024342:Amino Acids, Acidic / Q000378:metabolism*; D024361:Amino Acids, Basic / Q000378:metabolism*; D000818:Animals; D009154:Mutation; D011817:Rabbits; D019837:Ryanodine Receptor Calcium Release Channel / Q000302:isolation & purification / Q000378:metabolism*; D012519:Sarcoplasmic Reticulum / Q000737:chemistry / Q000378:metabolism*; D012604:Scorpion Venoms / Q000138:chemical synthesis / Q000235:genetics* / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D024342:Amino Acids, Acidic; D024361:Amino Acids, Basic; D019837:Ryanodine Receptor Calcium Release Channel; D012604:Scorpion Venoms; C105361:imperatoxin A