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. 2021 Jun 9;13(12):2885. doi: 10.3390/cancers13122885

Figure 2.

Figure 2

The TP73 gene architecture and generation of the p73 isoforms. (A) The scheme of the human TP73 gene structure. The human TP73 gene consists of 14 exons and additional alternative exon 3′ (shown as gray box). The exons are shown as boxes of different colors and noncoding sequences in black. There are two different promoters, the canonical promoter P1 upstream of exon 1 (giving rise to TAp73 isoforms) and the alternative P2 located in intron 3 (giving rise to ΔNp73 isoforms). The P1 transcript can be alternatively spliced leading to the expression of several N-terminally truncated isoforms (ΔEx2p73, ΔEx2/3p73, and ΔN′p73). Alternative splicing is also possible at the C-terminus, giving rise to seven potential isoforms (α, β, γ, δ, ε, ζ, and η). (B) Modular structure of the p73 protein isoforms. Functional protein domains are shown in different colors matching those used for the encoding exons of the TP73 gene in (A). The full-length TAp73α protein consists of a transactivation domain (TAD), a proline-rich domain (PRD), a DNA-binding domain (DBD), a nuclear-localization signal (NLS), an oligomerization domain (OD), a sterile α-motif (SAM), and an inhibitory domain (ID). There are 28 possible distinct p73 protein isoforms differing in the composition of the structural domains (as Δ’Np73 and ΔNp73 mRNAs translate into identical proteins).