Dog Hair Genetics 2

Retrievers are either black or brown depending on whether TRP-1 and TRP-2 are synthesized. If TRP-2 and TRP-1 are synthesized then the retriever is black, but if only TRP-2 is synthesized then the retriever is brown. In the case of a yellow lab however, neither TRP-1 or TRP-2 are synthesized. This is due to a mutation in the MSH gene that changes its conformation. Because of the change in conformation, the MSH can no longer bind to the MSH-R. The MSH-R is what signals to produce the TRP-1 and TRP-2 that causes pigmentation. This is what causes the hair of the yellow retriever to never become pigmented.