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.)

Locate the initiator codon within the XLαs segment.