Substrate-recognition component of the SCF (SKP1-CUL1-F-box protein)-type E3 ubiquitin ligase complex. May play a role in accumulation of expanded polyglutamine (polyQ) protein huntingtin (HTT) (By similarity). Protein modification; protein ubiquitination. Part of a SCF (SKP1-cullin-F-box) protein ligase complex consisting of FBXO25, SKP1, CUL1 and RBX1. Interacts directly with SKP1 and CUL1. Interacts (via C-terminus) with beta-actin (via N-terminus). In the nucleus, associates with a subnuclear dot-like structure. Colocalized with SKP1. Expressed in all brain tissue observed. The F-box is necessary for the interaction with SKP1. A chromosomal aberration involving FBXO25 is a cause of X-linked intellectual disability (XLID). Translocation t(X;8)(p11.22;p23.3) with SHROOM4.