Peculiar orthologue quality divergence in Ensembl

Question

[cdsouthan]

Since this is a somewhat extended graphics-based question I have put it up on my blog

http://cdsouthan.blogspot.se/2015/05/strange-case-of-endra-vs-b-in-ensembl.html

So why is the % id pattern of the orthologs (for the paralogous pair of Endothelin receptors) so very different?

[cdsouthan]

One for Emily_Ensembl perhaps?

Answer 1

[cdsouthan]

As an unusual but justified precedent I will answer my own question. It turns out the ENDRB receptor is prone to initiating a longer alternative 5' exon in humans and other species. So the Ensembl ortholog comparison picks up either the long or short form, leading to the sawtooth pattern in the chart. In comparison, for ENDRA the ortholog length is consistently the same across most species.