Loss of structured domains in the murine lineage.

(A) Domain composition of rodent GCNA proteins. Rabbit, which diverged from rodents 80 million years ago, serves as an outgroup. (B) Mouse and rat genomes contain non-transcribed pseudo-exons encoding structured domains. Human metalloprotease and zinc finger domains (encoded by human exons 10–12 and 12–13, respectively) aligned with translations of the corresponding mouse and rat non-transcribed exon remnants. Identical residues are indicated by stars, strongly similar residues by colons, and weakly similar residues by periods according to the Gonnet PAM 250 matrix (ClustalW). Dashes represent gaps in the alignment. Stop codons are indicated by red boxes and frameshifts by carets. Regions are color coded as follows: zinc metalloprotease-like (blue), zinc finger (purple), and HMG box (pink). The coordinates of the pseudo-exons in the mouse GRCm38/mm10 release are as follows (numbered according to corresponding human exons): exon 9 (ChrX: 101707035–101707103), exon 10 (ChrX: 101721392–101721498), exon 11 (ChrX: 101724005–101724133), exon 12 (ChrX: 101725798–101726001), and exon 13 (ChrX: 101727141–101727423). The coordinates of the pseudo-exons in rat RGSC 6.0/m6 are: exon 9 (ChrX: 71604116–71604175) and exon 10 (ChrX: 71610020–71610164). Sequences corresponding to human exons 11- 13 are not found in the rat genome. Note: primates have an in-frame stop codon before the HMG box (exon 13).