Effects of modification at the fifth residue of mu-conotoxin GIIIA with bulky tags on the electrically stimulated contraction of the rat diaphragm.
Mu-conotoxin GIIIA, a peptide toxin from the cone snail, blocks muscle-type sodium channels. Thr-5 of mu-conotoxin GIIIA, located on the opposite side of the active site in the globular molecule, was replaced by Cys to which the bulky tags were attached. The tagged mu-conotoxin GIIIA derivatives, except for the phospholipid-tagged one, exerted the biological activity with a potency slightly weaker than natural mu-conotoxin GIIIA. When the biotinylated tags of various lengths were added, the presence of avidin suppressed the action of the biotinylated toxins of <4 nm, but not with 5 nm. The bulky biotinylated tags are useful as a caliper to measure the depth of receptor sites in the channels.
Nakamura
M
M
Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa-ku, Nagoya, 464-8601, Japan. mnak@pc.uec.ac.jp
Ishida
Y
Y
Kohno
T
T
Sato
K
K
Oba
Y
Y
Nakamura
H
H
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001360:Avidin / Q000737:chemistry; D001710:Biotin / Q000737:chemistry; D002942:Circular Dichroism; D020916:Conotoxins / Q000138:chemical synthesis / Q000737:chemistry* / Q000235:genetics / Q000633:toxicity*; D003964:Diaphragm / Q000187:drug effects / Q000502:physiology; D004558:Electric Stimulation; D066298:In Vitro Techniques; D008297:Male; D008954:Models, Biological; D008969:Molecular Sequence Data; D009119:Muscle Contraction / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D013329:Structure-Activity Relationship
D020916:Conotoxins; C046101:conotoxin GIII; D001360:Avidin; D001710:Biotin