Fig. 3

Physicochemical properties of the intracellular and secreted peptides. a Sequence logos of the five N- and C-terminal amino acids of peptides from the secretome and cell. Colors correspond to amino acid chemical properties (green, purple, blue, red and black correspond to polar, neutral, basic, acidic and hydrophobic properties, respectively). b Boxplots showing differences in mean values of six the most significant “sigAA” indexes (P-value differences < e-25). KLEP840101: Net charge [83], FAUJ880111: Positive charge [84], ZIMJ680104: Isoelectric point [85], WOLS870103: Principal property value z3 [86], AURR980104: Normalized positional residue frequency at helix termini N’ [87] and SUEM840102: Zimm-Bragg parameter sigma × 1.0E4 [88]. c Locations of peptides identified in the secretome and cell peptidomes for the respective precursor proteins with membrane-spanning alpha helices (TMhelix)