Substrate-recognition component of the SCF (SKP1-CUL1-F-box protein)-type E3 ubiquitin ligase complex promoting ubiquitination and proteasomal degradation of specific target proteins including HNRNPU (PubMed:36285453). Regulates both the G2/M transition and anaphase entry in meiotic oocytes (By similarity). . (Microbial infection) Plays a positive role in latent HIV-1 activation. Mechanistically, promotes hnRNP U/HNRNPU ubiquitination, which leads to its degradation and abolishment of the interaction between hnRNP U and HIV-1 Rev mRNA. . This is the function of FBXO34 (F-box protein 34, ENSG00000178974).