FBXO18 belongs to the F-box protein family, whose members share the F-box, an approximately 40 amino acid motif. It has both DNA-dependent ATPase and DNA unwinding activities.

FBXO18 is a 1,043 amino acid protein encoded by the human gene FBXO18. FBXO18 belongs to the helicase family (UvrD subfamily) and contains one F-box domain. This nuclear protein is a DNA-dependent ATPase that unwinds double-stranded DNA in a 3' to 5' direction. FBXO18 also recognizes and binds to a variety of phosphorylated proteins and promotes their ubiquitination and degradation. It also interacts with Skp1 in the SCF E3 ubiquitin ligase complex consisting of Skp1, CUL-1, Rbx1 and FBXO18.