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

Figure 1.

Figure 1

The TP53 gene architecture and generation of the p53 isoforms. (A) The scheme of the TP53 gene structure. The human TP53 gene consists of 11 exons and two alternative exons 9β and 9γ. The exons are shown as boxes of different colors and noncoding sequences in black. Introns 2 (i2) and 4 (i4) are shown as boxes with a striped pattern. The TP53 gene can be transcribed from two different promoters, the canonical promoter P1 upstream of exon 1 (giving rise to the long p53/Δ40p53 isoforms) and the alternative P2 located in intron 4 (giving rise to the short Δ133/Δ160p53 isoforms). The TP53 mRNAs can be alternatively spliced at intron 2 or intron 9, producing isoforms with different N- and/or C-termini. There are four possible different start codons for mRNA translation (ATG1, ATG40, ATG133, and ATG160) resulting in protein isoforms of varying length. (B) Modular structure of the p53 protein isoforms. Functional protein domains are shown in different colors matching those used for the encoding exons of the TP53 gene in (A). The full-length p53α protein consists of two transactivation domains (TAD1 and TAD2), a proline-rich domain (PRD), a DNA-binding domain (DBD), a hinge domain (HD), an oligomerization domain (OD), and a C-terminal domain (CTD). There are 12 distinct p53 protein isoforms differing in the composition of the structural domains. Model adapted from [8,9,10].