Figure 3: Deep mutational scan identifies trafficking-defective variants.
A) Trafficking scores for nonsense, synonymous, and missense KV11.1 variants in the pilot region from Y545 to C555. Synonymous and nonsense variants were well-separated, with a mean score of 5 and 101, respectively. Missense variants had a range of scores from near-wildtype to loss-of-function, with a mean score of 55. B) A heatmap of the trafficking scores from the pilot region also displayed in A). KV11.1 residue number and identity are indicated in the leftmost column and amino-acid substitution is indicated on the top row. The black dot indicates synonymous variants. Color of the box indicates trafficking score compared to wildtype with blue as low expression to the plasma membrane and red as increased expression at the plasma membrane. Gray boxes indicate variants were absent in either the barcode libraries or trafficking results and therefore a trafficking score could not be determined. Out of the 220 variants assayed, 86 were WT-like (score > 75), 57 were mild loss-of-trafficking (75 > score > 50), 48 were loss-of-trafficking (50 > score > 25), and 73 were severe loss-of-trafficking (score < 25). Note the low trafficking scores of charged or polar amino-acids closer to the middle of the membrane (residues 550–555) (see Figure 4).