ROP proteins are a type of monomeric G proteins found in plants belonging to the Rho family. ROP binding to GTP or GDP determines its activity due to conformational changes within its structure. Within the G-domain of the structure are the G-box motifs G1-5. These motifs are formed during protein folding and are composed of conserved sequences that are responsible for nucleotide and magnesium binding as well as hydrolysis of GTP. Motifs G2 (switch I loop) and G3 (switch II loop) possess distinct conformations depending on GTP binding state. In addition, the G-domain contains a unique and conserved helical domain commonly found in Rho family proteins called αi.
Specific locations within the 3D ROP protein structure, including the amino acids 13-20, 60-64, and 118-121, act as binding sites during protein activity. The serine residue at amino acid 74 has been shown to be a potential protein activity regulation site through phosphorylation.