| Budget Amount *help |
¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 1998: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1997: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
In this study, systematic functional analysis was performed to 11 galectin genes found in the C.elegans genome library, which show apparent resemblance to the known nematode galectins (32 kDa and 16 kDa). The project strategy consist of ; 1) Estimation of expression level of individual genes by RT-PCR referring to EST data base, 2) cDNA cloning to determine exonhintron boundary and ORF (amino acid sequence), 3) bacterial expression and purification of recombinant proteins, LEC- 1-11, 4) analysis of biochemical properties of LEC- 1-1l, 5) analysis of sugar-binding properties, 6) identification of endogenous glycoligand receptors. As a result, there found to be five tandem-repeat type molecules (LEC-1-5) and five proto-type ones (LEC-7-l 1) significantly distinct from previously found I 6-kDa galectin (LEC-6). For lec-7, however, actual expression of the mature protein has not been confirmed, since a termination codon appeared in frame in the mis-predicted first intron. These two groups
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apparently form subfamilies showing >40% sequence identities within the groups. In particular, LEC-1-3 strikingly resemble one another (70% identities). Nevertheless, lec-3 expression seems to be restricted in embryo according to EST database, and in consistent with this observation, RT-PCR detected only limited amount of mRNA which was prepared from mixed stages of the worm (dominantly from adult worm). In addition, LEC-3 has a redundant 12-amino acid loop between two beta-strands which form a part of the sugar-binding region of galectins. Such a feature has never been observed with other galectins. LEC-4 and -5 show only moderate similarity in sequence, but shares a distinguished motif, "Arg-Gly-Asp" known as an attachment motif. LEC-8,10,1 1 are still more unique, having a redundant C-terminal tail (40-80 amino acids) and binding to metal-chelate column. Thus, many distinguished features were observed throughout this work which reflect diverse properties, and thus, maybe functions in the C.elegans galectin family. Less
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