M. Klemke et al. (2001) discovered an interesting coding phenomenon in which an exon within a neurologic hormone receptor gene in mammals appears to produce two different protein entities ( and ALEX). Following is the DNA sequence of the exon's end derived from a rat.
5'-gtcccaaccatgcccaccgatcttccgcctgcttctgaagATGCGGGCCCAG
The lowercase letters represent the initial coding portion for the protein, and the uppercase letters indicate the portion where the ALEX entity is initiated. (For simplicity, and to correspond with the RNA coding dictionary, it is customary to represent the coding (non-template) strand of the DNA segment.)
Are there any evolutionary advantages to having the same DNA sequence code for two protein products? Are there any disadvantages?
11. Translation
The Genetic Code