Rac proteins are categorized into three highly homologous proteins based on their expression levels—Rac1, Rac2, and Rac3, which play a central role in regulating response to inflammatory signals mediated by neutrophils, including chemotaxis, actin cytoskeleton remodeling, and production of superoxide by NADPH oxidase.
Rac is inactive when in a GDP-bound state and is activated upon exchange of its GDP for GTP, which enables downstream signaling to proceed.
The conformation of the guanine nucleotide binding domain is altered upon exchange of GDP for GTP, which permits effector binding.
Rac is a subfamily of the Rho family of GTPases, small (~21 kDa) signaling G proteins.
As other G proteins, Rac acts as a molecular switch, remaining inactive while bound to guanosine diphosphate (GDP) and activated once guanine nucleotide exchange factors (GEFs) remove GDP, permitting guanosine triphosphate (GTP) to bind.
When bound to GTP, Rac is activated, and participates in the regulation of cell movement, through its involvement in structural changes to the actin cytoskeleton.
By changing the cytoskeletal dynamics within the cell, Rac-GTPases facilitate the recruitment of neutrophils to the infected tissues, and to regulate phagocytosis.
Rac activation is required for reactive oxygen species production involved in the formation of NETs (neutrophil extracellular traps) , and facilitates the pathogen and debris clearance by neutrophils, and the reduction of inflammation.
The abnormal activities of Rac including its hyperactivation, resistance to degradation, and abnormal localization of its signaling protein components were found to facilitate the development of cancerous cells and resist to anticancer treatment.
Hyperactivation of Rac increases memory decay whereas its inhibition prevents interference-induced forgetting and slows down passive memory decay.