Sequence at the 5′ end of the hsREV3 cDNA. Nucleotides shown in uppercase are the first 352 nt of the major mRNA species, whereas the nucleotides in lowercase are the 128-nt insertion found in the variant. The ORF for hsREV3 starts at the ATG labeled In2, and this reading frame possesses an upstream termination codon, labeled T1. The ATG labeled In1 is upstream and out of frame with respect to In2 and could direct the synthesis of a 106 amino acid polypeptide, terminating at T4. For the 128-nt-insertion variant, the ORF starting at In1 would be terminated at T3, encoding a 77 amino acid polypeptide, whereas translation initiated at In2 would terminate at T2, yielding a 47-aa polypeptide.