cDNA cloning and characterization of Type I procollagen α1 chain in the skate Raja kenojei

A full-length cDNA of the Type I procollagen α1 [pro-α1(I)] chain (4388 bp), coding for 1463 amino acid residues in the total length, was determined by RACE PCR using a cDNA library constructed from 4-week embryo of the skate Raja kenojei. The helical region of the skate pro-α1(I) chain consisted of 1014 amino acid residues — the same as other fibrillar collagen α chains from higher vertebrates. Comparison on denaturation temperatures of Type I collagens from the skate, rainbow trout (Oncorhynchus mykiss) and rat (Rattus norvegicus) revealed that the number of Gly-Pro-Pro and Gly-Gly in the α1(I) chains could be directly related to the thermal stability of the helix. The expression property of the skate pro-α1(I) chain mRNA and phylogenetic analysis with other vertebrate pro-α1(I) chains suggested that skate pro-α1(I) chain could be a precursor form of the skate Type I collagen α1 chain. The present study is the first evidence for the primary structure of full-length pro-α1(I) chain in an elasmobranch.