When talking about master genes and BMP4, is the variation between species due to differences in the nucleotide sequence of the BMP4 gene or the genes it controls?
Hello again,
Yes, mutations and differences do exist in bmp4 (the master gene itself is represented with lower case letters), and the only thing that changes is the bmp4 gene itself (more specifically the pro domain region,
https://en.wikipedia.org/wiki/Protein_domain). The mutations (which only occur in a specific region) means that the product of the gene is not affected in any way, the protein BMP4 (capital letters) is still the protein itself, but what is affected tho is the location, timing, and persistence of gene expression.
The genes bmp4 control do not change tho, it's just a very specific part of the bmp4 gene that's different.