Exon in a sentence as a noun

It is not called "Selfish Adenine" or "Selfish exon".Your analogy is interesting.

I may be misinterpreting what you said but it seems as though you consider 'start' 'stop' 'intron' 'exon' 'suppress' as properties of transcription factors.

Exon definitions

noun

sequence of a gene's DNA that transcribes into protein structures; "exons are interspersed with introns"