Jump to Main Content
Complete primary structure of rainbow trout type I collagen consisting of Î±1(I)Î±2(I)Î±3(I) heterotrimers
- Saito, Masataka, Takenouchi, Yoshitaka, Kunisaki, Naomichi, Kimura, Shigeru
- European journal of biochemistry 2001 v.268 no.10 pp. 2817-2827
- Oncorhynchus mykiss, amino acids, cDNA libraries, collagen, complementary DNA, denaturation, digestion, fibroblasts, fish, heat, imino acids, muscles, phylogeny, temperature
- The subunit compositions of skin and muscle type I collagens from rainbow trout were found to be Î±1(I)Î±2(I)Î±3(I) and [Î±1(I)]2Î±2(I), respectively. The occurrence of Î±3(I) has been observed only for bonyfish. The skin collagen exhibited more susceptibility to both heat denaturation and MMPâ13 digestion than the muscle counterpart; the former had a lower denaturation temperature by about 0.5âÂ°C than the latter. The lower stability of skin collagen, however, is not due to the low levels of imino acids because the contents of Pro and Hyp were almost constant in both collagens. On the other hand, some cDNAs coding for the Nâterminal and/or a part of tripleâhelical domains of proÎ±(I) chains were cloned from the cDNA library of rainbow trout fibroblasts. These cDNAs together with the previously cloned collagen cDNAs gave information about the complete primary structure of type I procollagen. The main tripleâhelical domain of each proÎ±(I) chain had 338 uninterrupted GlyâXâY triplets consisting of 1014 amino acids and was unique in its high content of GlyâGly doublets. In particular, the bonyfishâspecific Î±(I) chain, proÎ±3(I) was characterized by the small number of GlyâProâPro triplets, 19, and the large number of GlyâGly doublets, 38, in the tripleâhelical domain, compared to 23 and 22, respectively, for proÎ±1(I). The small number of GlyâProâPro and the large number of GlyâGly in proÎ±3(I) was assumed to partially loosen the tripleâhelical structure of skin collagen, leading to the lowerÂ stability of skin collagen mentioned above. Finally, phylogenetic analyses revealed that proÎ±3(I) had diverged from proÎ±1(I). This study is the first report of the complete primary structure of fish type I procollagen.