A. Unique structural features in mycobacterial ALPS. The structure of MptpB, left (PDB ID 2OZ5) is shown as a ribbon diagram. The mycobacterial insertion 1 (magenta) and insertion 2 (green) are shown together with the alpha helix (orange) conserved in ALPs (C3). The structure of human PTP1B (PDBID 1AAX) is shown on the right. In orange is the analogous region to C3, which adopts a non-helical conformation in PTPs. The active site P-loop is shown in red. Ribbon diagrams generated using PyMol (DeLano Scientific LLC). B. Domain organisation in lipid phosphatases. PTEN and MTM type lipid phosphatases have a phosphatase PTP domain and additional lipid binding domains like PH-GRAM, C2, FYVE that exert allosteric control and anchor the PTP domain to different membrane locations. ALP and PFA lipid phosphatases lack the classic lipid binding domains, only Lmo1800 contains a predicted lipid attachment sequence.