Figure 3.

A proposed flow chart to aid researchers to identify and classify PPE proteins in order to formulate testable hypotheses. When interested in a PPE gene or protein, a first step can be to verify it is indeed a functional PPE protein, by investigating presence of the defining characteristics (Start at the left top of the flow chart). A following step is to classify the PPE‐protein as a PPE‐PPW (Green), PPE‐SVP (Red), PPE‐MPTR (Yellow), or other (blue), based on its C‐terminal domains (or lack thereof).