Alternative splicing in the COL5A1 C-propeptide region and conservation of alternatively spliced exon sequences across species. (A) Amino acid sequences are shown for exons A and B for human mouse, chick and zebrafish. (B) Restriction with EcoRI, which cuts within exon A, but not exon B sequences, or SexAI, which cuts within exon B but not exon A sequences, demonstrates varying ratios of exon A and B sequences in human placenta (P) and liver (L). The first two lanes are uncut cDNA. (C) Percentages of similarity and identity (parentheses) between the amino acid sequences of exons A and B in the pro-α1(V) genes of human, mouse, chick, and zebrafish were obtained by alignment using the BLAST Basic Local Alignment Search Tool.