cDNA cloning and expression analysis of new members of the mammalian F-boxprotein family

F-box proteins are critical components of the SCF ubiquitin-protein ligase complex and are involved in substrate recognition and recruitment for ubiqu itination and consequent degradation by the proteasome. We have isolated cD NAs encoding a further 10 mammalian F-bos proteins. Five of them (FBL3 to F BL7) share structural similarities with Skp2 and contain C-terminal leucine -rich repeats. The other 5 proteins have different putative protein-protein interaction moths. Specifically, FBS and FBWD4 proteins contain Sec7 and W D40-repeat domains, respectively. The C-terminal region of FBA shares simil arity with bacterial protein ApaG while FBG2 shows homology with the F-box protein NFB42. The marked differences in F-box gene expression in human tis sues suggest their distinct role in ubiquitin-dependent protein degradation . (C) 2000 Academic Press.