Cooperates with the reticulon proteins and tubule-shaping DP1 family proteins to generate and maintain the structure of the tubular endoplasmic reticulum network. Has GTPase activity, which is required for its function in ER organization. Enriched in the cortical ER. Concentrated in punctae along the ER tubules. Belongs to the TRAFAC class dynamin-like GTPase superfamily. GB1/RHD3 GTPase family. RHD3 subfamily.