Draft #44

The TYRP1 gene in Canis Lupus Familiarus, known commonly as the domesticated dog species, has been well studied. Since the genes of dogs have been sequenced and thousands of alleles compared, it was revealed that this gene, TYRP1, contains a very common and highly conserved mutation. The wildtype DNA sequence for the gene contains a segment 5'-TGGGGGAA-3'. In the mutation the sequence is simply 5'-TGGAA-3'. This shows a three nucleotide deletion that removes a set of three Gs. The reason this mutation is able to be so conserved is because three nucleotides form one single codon, allowing for the deletion to not cause a frame shift in the gene so that only one single amino acid is missing and the remaining correct amino acids are conserved. This mutation causes a disfunctional protein that acts as an enzyme in melanocyte cells that produce colored pigment in the dog hairs. Without a functional TYRP1, a brown pigment cannot be transformed into a black pigment. Because this defect has no toxicity in the accumulation of the brown pigment, the mutation was never selected against and gained frequency in population, also thanks to breeding.