Sequence logo representations of the teleost fish periostin repeat consensus and of the consensus sequences from tetrapod exons of the periostin C-terminal region. (A) The periostin repeat sequence logo for teleosts was obtained from an alignment of the 13 aa repeat units of periostin exon 18=19 (see main text) from four teleost species (Dr, Ga, Tn, Tr). The starting amino acid (proline) is arbitrarily chosen (see also Methods). (B - K) The exon-specific sequence logo representations were obtained from alignments of the respective periostin exons from seven tetrapod species considered here (Hs, Mm, Md, Oa, Gg, Ac, Xt). Exceptions are (G), the Xt exon 19 cluster, where a sequence alignment of exons 19 and 19A - 19H (see main text) was the basis for the sequence logo, and (J), exon 21V22, which was based only on sequences from Md, Oa, Gg, Ac, and Xt. (L) A matrix dot plot showing similarities between the teleost repeat consensus (horizontal, as duplet for clarity) and the sequential tetrapod exon consensus sequences (vertical), with the exon sizes indicated on the side. The dot plot is color-coded (white-yellow-orange-red-black), with white indicating highest similarity and black indicating no similarity. Both this dot plot and the sequence logos indicate the strong similarities between the teleost repeats and the tetrapod C-terminal exons found in the alternatively spliced exons 17 - 21V22 (see main text).