This gene encodes a member of the Rho family of small GTPases, which cycle between inactive GDP-bound and active GTP-bound states and function as molecular switches in signal transduction cascades. In active state binds to a variety of effector proteins to regulate cellular responses. Rho proteins promote reorganization of the actin cytoskeleton and regulate cell shape, attachment, and motility. The encoded protein is an important signalling protein for sarcomere assembly and has been shown to play a significant role in the exocytosis of the solute carrier family 2, facilitated glucose transporter member 4 and other proteins, possibly acting as the signal that turns on the membrane fusion machinery. Involved in epithelial cell polarization processes. May play a role in CFTR trafficking to the plasma membrane. Causes the formation of thin, actin-rich surface projections called filopodia. Three related pseudogene have been identified on chromosomes 2 and 14. Interacts with CDC42EP4 in a GTP-dependent manner. Interacts with ARHGAP33/TCGAP (By similarity). Interacts with CDC42EP1, CDC42EP2, CDC42EP3, PARD6A, PARD6G (and probably PARD6B) in a GTP-dependent manner. Part of a quaternary complex containing PARD3, some PARD6 protein (PARD6A, PARD6B or PARD6G) and some atypical PKC protein (PRKCI or PRKCZ). Interacts with EXO70 in a GTP-dependent manner. Interacts with GOPC.