Substrate recognition component of a SCF (SKP1-CUL1-F-box protein) E3 ubiquitin-protein ligase complex which mediates the ubiquitination and subsequent proteasomal degradation of target proteins. Acts as a positive regulator of the BMP signaling pathway). Required for dorsal/ventral pattern formation (By similarity. Protein modification; protein ubiquitination. Part of the SCF (SKP1-CUL1-F-box) E3 ubiquitin-protein ligase complex SCF(FBXL15). Belongs to the FBXL15 family.