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Rap1 is a small GTPase that modulates adhesion of T cells by regulating inside-out signaling through LFA-1. The bulk of Rap1 is expressed in a GDP-bound state on intracellular vesicles. Exocytosis of these vesicles delivers Rap1 to the plasma membrane, where it becomes activated. We report here that phospholipase D1 (PLD1) is expressed on the same vesicular compartment in T cells as Rap1 and is translocated to the plasma membrane along with Rap1. Moreover, PLD activity is required for both translocation and activation of Rap1. Increased T-cell adhesion in response to stimulation of the antigen receptor depended on PLD1. C3G, a Rap1 guanine nucleotide exchange factor located in the cytosol of resting cells, translocated to the plasma membranes of stimulated T cells. Our data support a model whereby PLD1 regulates Rap1 activity by controlling exocytosis of a stored, vesicular pool of Rap1 that can be activated by C3G upon delivery to the plasma membrane.

Original publication




Journal article


Mol cell biol

Publication Date





3297 - 3306


Animals, Biological Transport, Active, COS Cells, Cell Adhesion, Cell Membrane, Chlorocebus aethiops, Cytoplasmic Vesicles, Female, Guanine Nucleotide-Releasing Factor 2, HeLa Cells, Humans, In Vitro Techniques, Jurkat Cells, Mice, Mice, Inbred C57BL, Models, Biological, Phospholipase D, Recombinant Proteins, T-Lymphocytes, Up-Regulation, rap1 GTP-Binding Proteins