頁籤選單縮合
題名 | Characterization of γS-Crystallin Isoforms from a Catfish: Evolutionary Comparison of Various γ-, γS-, and β-Crystallins= |
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作者 | Chiou,Shyh-horng; Pan,Fu-ming; Peng,Hsuan-wan; Chao,Yen-kai; Chang,Wen-chang; |
期刊 | 中央研究院生物化學研究所論文集 |
出版日期 | 19980000 |
卷期 | 24 1998[民87.] |
頁次 | 頁106-113 |
分類號 | 361.19 |
語文 | eng |
關鍵詞 | γS-crystallin; Catfish; β-crystallins; γ-crystallins; |
英文摘要 | γS-Crystallin from catfish eye lenses, formerly designated β s-crystallin in mammalian lenses, is structurally characterized in this study by cDNA cloning and sequencing. To facilitate sequence characterization of γ S-crystallin with structural properties lying between β - and γ -crystallins, a cDNA mixture was constructed from the poly(A) �� mRNA isolated from catfish eye lenses, and amplification by polymerase chain reaction (PCR) was carried out to obtain nucleotide segments encoding multiple γ S-crystallin isoforms. Sequencing several positive clones revealed that at least two distinct isoforms exist in the γ S-crystallin class of this teleostean fish, similar to the authentic - γ -crystallin family characterized previously in species of the piscine class. Comparison of protein sequences encoded by two representative catfish γ Sl and - γ S2 cDNAs with the published sequences of β -, γ -, and γ S-crystallins from shark, carp, bullfrog, bovine, and human lenses indicates that there is about 20-50% sequence homology between catfish γ S-crystallins and various members of the related β / γ -crystallin superfamily from different evolutionary classes, with a higher sequence similarity being found between catfish γ S- and mammalian γ -crystallins than between catfish γ S- and bovine or carp γ S-crystallins. Phylogenetic trees constructed on the basis of the nucleotide and protein sequence divergence among various β -, γ -, and γ S-crystallins corroborate the closer relatedness of catfish γ S- to authentic γ -crystallin than to bovine and carp γ S-crystallins. The results suggest that evolution of catfish γ S-crystallins follows a different path from that of bovine and carp - γ S-crystallins and may represent a more ancient offshoot from the anstrl γ / γ S conding gene than carp and bovine γ S-crystallins. |
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