Rac G Protein, also known as Rac, is a member of the Rho family of small GTP-binding proteins. It is a key regulator of diverse cellular processes, including cytoskeletal dynamics, cell adhesion, cell migration, and intracellular signaling pathways.
At the molecular level, Rac functions as a molecular switch, cycling between an inactive GDP-bound state and an active GTP-bound state. The activation of Rac is tightly regulated by guanine nucleotide exchange factors (GEFs), which promote the exchange of GDP for GTP, as well as GTPase-activating proteins (GAPs), which enhance the intrinsic GTP hydrolysis activity of Rac.
Once activated, Rac plays a central role in the modulation of actin cytoskeleton dynamics by regulating the activity of downstream effector proteins, such as Wiskott-Aldrich syndrome protein (WASP) and p21-activated kinase (PAK). This leads to the reorganization of actin filaments and the formation of membrane protrusions, facilitating cell migration and invasion. Rac also enables the activation of various signaling pathways, including those mediated by mitogen-activated protein kinases (MAPKs) and phosphoinositide 3-kinase (PI3K), which control cell proliferation, survival, and differentiation.
Furthermore, Rac is involved in the regulation of cell-cell adhesion and cell-matrix interactions through the modulation of the assembly and turnover of focal adhesions and adherens junctions. Dysfunction or dysregulation of Rac can contribute to various diseases, including cancer, cardiovascular disorders, neurodegenerative diseases, and immunological disorders.
