Fig 1: Overexpression of active PTPRJ diminishes CEACAM3-mediated phagocytosis.A, schematic representation of myristoylated (myr-) protein phosphatase domains lacking the extracellular and the transmembrane domain. PTPRS, PTPRF, and PTPRG harbor, in addition to the catalytically active phosphatase domain (dark gray), a second catalytically inactive domain (light gray). B, 293T cells were cotransfected to express CEACAM3-GFP together with the indicated phosphatase domains fused to mCherry. Equal CEACAM3-GFP expression levels and expression of the different myr-phosphatase-mCherry constructs were analyzed by Western blotting using α-GFP (upper panel) and α-mCherry (middle panel) antibodies. Probing of the samples with α-vinculin (lower panel) served as loading control. C, cells from (B) were infected with Opa52-expressing (Opa52) or Opa-negative (Opa-) N. gonorrhoeae (MOI 30) for 45 min. Internalized bacteria were enumerated by gentamicin protection assays. Bars show mean ± SEM of three independent experiments performed in triplicates. n.s., not significant; ∗∗∗p < 0.001. D, 293T cells were cotransfected with plasmids encoding GFP-tagged CEACAM3 or GFP alone together with the indicated mScarlet-tagged myristoylated phosphatase domain or mScarlet alone. Cells were infected with PacificBlue-labeled Opa52-expressing N. gonorrhoeae for 30 min, fixed, and analyzed by confocal microscopy. Insets show 3× magnification of boxed areas. Bars represent 10 μm (corresponding to 3.3 μm for insets). CEACAM3, carcinoembryonic antigen-related cell adhesion molecule 3; PTPR, receptor-type protein tyrosine phosphatase.