F-box proteins that function with Skp1. A. The SCF complex. The F-box protein is linked to the core complex through interaction between Skp1 and the F-box. Ubiquitin is transferred from a ubiquitin-conjugating enzyme (E2) onto substrates recruited by the F-box protein. After poly-ubiquitination, the substrate is recognized by the proteasome and degraded (not shown). B. The yeast CBF3 centromere binding complex. Activation of Ctf13 requires association with Skp1. This allows formation of the structural core of the budding yeast centromere binding complex (CBF) comprising Skp1, Ctf13, Cep3 and Ndc10. Ctf13 stability is controlled by ubiquitination dependent on a SCF complex containing the Cdc4 F-box protein. C. The RAVE complex. Skp1 forms the RAVE complex with Rav1 (containing a putative F-box motif) and Rav2. RAVE interacts with the V1 domain of the vacuolar membrane (H+)-ATPase (V-ATPase) and this is required for stable assembly of the V1 domain with the membrane associated V0 domain. Note that V1 and V0 are composed of several proteins. D. The Skp1-Rcy1 recycling complex. The Rcy1 F-box protein regulates the early endosomes (EE) to trans-golgi network (TGN) recycling. The Snc1 SNARE protein is endocytosed into early endosomes and is transported back to the plasma membrane via the trans-golgi network. Rcy1 binds Snc1 and regulate its sorting and marking for recycling by phosphorylation (not shown).