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Summary of Research Projects (Supports in 2004
Fiscal Year)
| Subjects |
Functional expression of puffer fish muscle sodium
channel, and transportation and accumulation of tetrodotoxin and saxitoxin
in puffer fish involved in the toxin binding protein in its plasma |
| Representative researcher |
Graduate School of Agricultural Science,Tohoku University
Mari Yotsu-YAMASHITA |
| Puffer fish accumulate high level of
tetrodotoxin (TTX) in their tissues. We are interested in the toxin resistance
and accumulation of puffer fish. We previously cloned a cDNA coding a muscle
voltage-gated sodium channel of the puffer fish, Fugu pardalis (fMNa1),
and found a mutation which was supposed to be involved in TTX-resistance.
In this study, we attempted to express fMNa1 in mammalian cell line to
examine the functions. Although we have not succeeded expression of fMNa1
itself, the mutation found in fMNa1 (F385N) was introduced to TTX-sensitive
rat brain sodium channel II (rNav1.2) and this mutant was expressed
in HEK293. By electrophysiological experiments using the patch clamp method,
the value of IC50 against TTX of F385N mutant was estimated
to be approximately 3,000 fold larger than that of the wild type, suggesting
that fMNa1 was a TTX-resistant sodium channel at least due to this mutation.
Further, we previously found a soluble glycoprotein, saxitoxin (STX) and
TTX binding protein (PSTBP) in the plasma of F. pardalis. In this
study, we prepared anti-serum against the protein part of PSTBP expressed
in E. coli, and studied localization of PSTBP in tissues of F. pardalis by
Western blot analysis and by immunohistochemical staining by using this
anti-serum. |
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