Table 1 Number of ATP2A genes with and without an intron at the motif AAIPEGLPAV in 15 species.

From: A segmental genomic duplication generates a functional intron

Species # ATP2A with intron # ATP2A w/o intron
Human 1 2
Mouse 1 2
Opossum 1 2
Platypus 1 2
Chicken 1 2
Frog 1 2
Zebrafish 3 4
Fugu 3 2
Stickleback 2 4
Medaka 2 4
Lamprey 0 1
Sea squirt 0 4 (tandem)
Lancelet 0 2 (tandem)
Sea urchin 0 1
Sea anemone 0 2
  1. Tetrapods (that is, Human through Frog above) all have three copies, of which one has the intron. These copies can be shown to have originated from two rounds of whole-genome duplication (WGD) and subsequent single-copy loss. Teleost fish (Zebrafish-Medaka) have 5–7 copies, consistent with having undergone an extra round of WGD. Because fugu and zebrafish have more than two copies with an intron, the insertion of the intron probably happened between the two rounds of WGD. No genes with this intron are found outside vertebrates (Lamprey and below).