A new subfamily of structurally related human F-box proteins

Gene. 2002 Aug 21;296(1-2):11-20. doi: 10.1016/s0378-1119(02)00867-3.


F-box proteins, a critical component of the evolutionary conserved ubiquitin-protein ligase complex SCF (Skp1/Cdc53-Cullin1/F-box), recruit substrates for ubiquitination and consequent degradation through their specific protein-protein interaction domains. Here, we report the identification of full-length cDNAs encoding three novel human F-box proteins named FBG3, FBG4 and FBG5 which display similarity with previously identified NFB42 (FBX2) and FBG2 (FBX6) proteins. All five proteins are characterized by an approximately 180-amino-acid (aa) conserved C-terminal domain and thus constitute a third subfamily of mammalian F-box proteins. Analysis of genomic organization of the five FBG genes revealed that all of them consist of six exons and five introns. FBG1, FBG2 and FBG3 genes are located in tandem on chromosome 1p36, and FBG4 and FBG5 are mapped to chromosome 19q13. FBG genes are expressed in a limited number of human tissues including kidney, liver, brain and muscle tissues. Expression of rat FBG2 gene was found related to differentiation/proliferation status of hepatocytes. Specifically, FBG2 mRNA was expressed in foetal liver, decreased after birth and re-accumulated in adult liver. Expression of FBG2 was strongly inhibited in hepatoma cells by okadaic acid.

Publication types

  • Comparative Study

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Cell Cycle Proteins / genetics*
  • Chromosome Mapping
  • Chromosomes, Human, Pair 1 / genetics
  • Chromosomes, Human, Pair 19 / genetics
  • Cloning, Molecular
  • DNA, Complementary / chemistry
  • DNA, Complementary / genetics
  • Exons
  • Female
  • Gene Expression
  • Gene Expression Regulation, Developmental
  • Genes / genetics
  • Humans
  • Introns
  • Liver / embryology
  • Liver / metabolism
  • Male
  • Molecular Sequence Data
  • Multigene Family / genetics*
  • Phylogeny
  • Pregnancy
  • Protein Isoforms / genetics
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Sequence Alignment
  • Sequence Analysis, DNA
  • Sequence Homology, Amino Acid
  • Tumor Cells, Cultured


  • Cell Cycle Proteins
  • DNA, Complementary
  • Protein Isoforms
  • RNA, Messenger

Associated data

  • GENBANK/AF386743
  • GENBANK/AF393484
  • GENBANK/AF436061
  • GENBANK/AY040878