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. Author manuscript; available in PMC: 2018 Feb 1.
Published in final edited form as: Trends Genet. 2016 Dec 21;33(2):129–142. doi: 10.1016/j.tig.2016.11.007

Figure 1. Functional Organization of Bicistronic Genes.

Figure 1

A. Two subunits of a multi-subunit complex whose expression is coordinated in a single transcript: each Open Reading Frame (ORF) codes for a specific subunit of a larger protein complex. B. Functionally similar gene products that are differentially co-expressed: a primary protein is expressed through canonical cap-dependent translation while a secondary and functionally similar protein is differentially expressed through a cap-independent mechanism. C. Functionally distinct gene products that have programmatically-related expression: expression of two differentially functioning proteins is coupled with their operation in a particular biological pathway. Category 3 appears with both tandem and overlapping reading frames. D. Signaling proteins generated by stimulus-coupled protease cleavage or by cap-independent translation: two overlapping ORFs code for necessary products for signal transduction, the primary product is a receptor that initiates signal transduction upon ligand binding while the secondary product is a constitutively active signal.