Acts as a central regulator in the cell wall integrity signaling pathway, which is regulated by the cell cycle and in response to various types of cell wall stress. Integrates signals from different cell surface sensors, and activates a set of effectors, regulating processes including beta-glucan synthesis at the site of wall remodeling, gene expression related to cell wall biogenesis, organization of the actin cytoskeleton, and protein- and secretory vesicle-targeting to the growth site. Activates the protein kinase C (PKC1) MAP kinase cascade, the beta-1,3-glucan synthase (FKS1), the formin BNI1, the exocyst component SEC3 and the transcription factor SKN7. GTP + H2O = GDP + H(+) + phosphate Alternates between an inactive form bound to GDP and an active form bound to GTP. Activated by the guanine nucleotide-exchange factors (GEFs) ROM1, ROM2 and TUS1, and inactivated by GTPase-activating proteins (GAPs) BAG7, BEM2, LRG1, and SAC7, and the Rho GDP-dissociation inhibitor RDI1. The different GAPs regulate RHO1 in a target-specific manner. Interacts with BEM4; the interaction is direct (PubMed:8754839, PubMed:8754840). Interacts with SEC3; the interaction is direct (PubMed:11283608). Interacts with the GAP BAG7 (PubMed:11591390, PubMed:12207708). Interacts with the GAP LRG1 (PubMed:11447600). Interacts with the GAP SAC7 (PubMed:11447600, PubMed:9038344). Interacts with the GAP RDI1 (PubMed:9242378). Interacts with the 1,3-beta-glucan synthase component FKS1 (PubMed:8602515). Interacts with the protein kinase PKC1 (PubMed:8621575, PubMed:8846785). Interacts with the G protein beta subunit STE4 (PubMed:12660244). Interacts with SKN7 (PubMed:9535835). Interacts with TUS1 (PubMed:11839800). Interacts with BNI1 (PubMed:8947028). Plasma membrane-associated at sites of polarized growth such as incipient bud sites, bud tips, the bud neck during cytokinesis, and the neck and tip of mating projections. Also found on internal membranes of endosomes and peroxisomes. Belongs to the small GTPase superfamily. Rho family.