Figure 1. An alternative reading frame within the Ink4a locus encodes a disordered, polycationic protein.
(A) Ink4a locus encodes for two unrelated tumor suppressor proteins, p14Arf and p16Ink4A; exons encoding for Arf and p16Ink4A are color-coded blue and purple, respectively. Dual colored exons represent overlap coding regions. (B) Net charge per residue analysis (prepared using CIDER, http://pappulab.wustl.edu/CIDER/) of the human (p14Arf) and mouse (p19Arf) protein sequences. Charge distribution in the C-terminal region of p19Arf is more uniform compared to p14Arf, and thus the location of a possible R2 motif is unclear.