Exon 3 of the NUMB Gene Emerged in the Chordate Lineage Coopting the NUMB Protein to the Regulation of MDM2.

Confalonieri S, Colaluca IN, Basile A, Pece S, Di Fiore PP.

G3 (Bethesda). 2019 Oct 7;9(10):3359-3367. doi: 10.1534/g3.119.400494.

Ciona NUMB can inhibit ubiquitination of P53 by MDM2. This and a phylogenetic analysis demonstrates that PTB-long isoform encoded by Exon3 is a Chordate invention. O. dioica has 2 NUMB genes, more similar to NUMB than to vertebrate-specific NUMBL. Their intron/exon structures are different from any other organism.