Related Experiment Video
Updated: Aug 16, 2026

"Phagosome Closure Assay" to Visualize Phagosome Formation in Three Dimensions Using Total Internal Reflection Fluorescent Microscopy (TIRFM)
Published on: August 26, 2016
An essential function for the calcium-promoted Ras inactivator in Fcgamma receptor-mediated phagocytosis
Jun Zhang1, Jian Guo, Ivan Dzhagalov
1Department of Immunology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Abstract:
Fc receptor (FcR)-mediated phagocytosis requires activation of the Rho GTPases Cdc42 and Rac1, but how they are recruited to the FcR is unknown. Here we show that the calcium-promoted Ras inactivator (CAPRI), a Ras GTPase-activating protein, functions as an adaptor for Cdc42 and Rac1 during FcR-mediated phagocytosis. CAPRI-deficient macrophages had impaired FcgammaR-mediated phagocytosis and oxidative burst, as well as defective activation of Cdc42 and Rac1. CAPRI interacted constitutively with both Cdc42 and Rac1 and translocated to phagocytic cups during FcgammaR-mediated phagocytosis. CAPRI-deficient mice had an impaired innate immune response to bacterial infection. These results suggest that CAPRI provides a link between FcgammaR and Cdc42 and Rac1 and is essential for innate immune responses.
Related Concept Videos
Calmodulin-dependent Signaling
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
Rab Cascades
IP3/DAG Signaling Pathway
Small GTPases - Ras and Rho
Three regulatory proteins control their activity:
Immune Surveillance by NK Cells and Phagocytes
Natural Killer Cells: The Fast Responders
NK cells are large granular lymphocytes found in the blood and lymphatic system. These...
Rab Proteins
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...

