Structural gene

A structural gene is a gene that codes for any RNA or protein product other than a regulatory factor (i.e. regulatory protein). Structural genes are typically viewed as those containing sequences of DNA corresponding to the amino acids of a protein that will be produced, as long as said protein does not function to regulate gene expression. Structural gene products include enzymes and structural proteins. Also encoded by structural genes are non-coding RNAs, such as rRNAs and tRNAs (but excluding any regulatory miRNAs and siRNAs).

The distinction between structural and regulatory genes can be traced back to 1959 and work by Pardee, Jacob, and Monod—the so-called PaJaMo experiment—on the lac operon and the synthesis of proteins in E. coli. In that system, a single regulatory protein was detected that affected the transcription of the other proteins now known to compose the lac operon.