Fig. 4

Distribution of splice sites in hemocyanin FUs. Splice site positions (arrows) are shown within the overlay of FU-coding sequences of hemocyanin genes (grey bar; darker parts: copper binding sites). They are spread over the sequence in clusters. Letters above indicate in which FU and in which molluscan group (color) they are located. About 48% of all internal introns are located at identical positions as introns in one or two other FUs (multiple splice site positions; marked with black dots). Positions that are unique for one splice site are marked with an open dot. The pink arrowhead shows the only internal introns which are located at the identical position within Tectipleura and Lepetellida (same position in ortholog FU (FU-a))