Cryptic initiation at the human D4 receptor reveals a functional role for the amino terminus

The amino terminus of the human D4 receptor was investigated for its cryptic initiation site in the first transmembrane region. Deletion of this amino terminus did not prevent expression, which continued to express up to 70% of the D4 control levels. This evidence supports an alternative site for translation initiation in the transmembrane region, hypothesized to be at nucleotide +112. Possible role of the amino terminus is stabilizing the active site for the functional activity of the receptor.