Cloning and functional analysis of human p51, which structurally and functionally resembles p53

Nat Med. 1998 Jul;4(7):839-43. doi: 10.1038/nm0798-839.


The p53 tumor suppressor gene, which is induced by DNA damage and/or stress stimuli, causes cells to undergo G1-arrest or apoptotic death; thus it plays an essential role in human carcinogenesis. We have searched for p53-related genes by using degenerate PCR, and have identified two cDNA fragments similar to but distinct from p53: one previously reported, p73, and the other new. We cloned two major splicing variants of the latter gene and named these p51A and p51B (a human homologue of rat Ket). The p51A gene encodes a 448-amino-acid protein with a molecular weight of 50.9 kDa; and p51B, a 641-amino-acid protein with a molecular weight of 71.9 kDa. In contrast with the ubiquitous expression of p53, expression of p51 mRNA was found in a limited number of tissues, including skeletal muscle, placenta, mammary gland, prostate, trachea, thymus, salivary gland, uterus, heart and lung. In p53-deficient cells, p51A induced growth-suppression and apoptosis, and upregulated p21waf-1 through p53 regulatory elements. Mutations in p51 were found in some human epidermal tumors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alternative Splicing*
  • Amino Acid Sequence
  • Animals
  • Apoptosis
  • Cats
  • Cell Division
  • Chickens
  • Cloning, Molecular
  • Cyclin-Dependent Kinase Inhibitor p21
  • Cyclins / genetics
  • DNA-Binding Proteins / genetics*
  • DNA-Binding Proteins / physiology
  • Gene Expression Regulation
  • Genes, Tumor Suppressor
  • Humans
  • Mice
  • Molecular Sequence Data
  • Phosphoproteins*
  • Promoter Regions, Genetic
  • Salmon
  • Sequence Homology, Amino Acid
  • Tissue Distribution
  • Trans-Activators*
  • Transcription Factors
  • Tumor Cells, Cultured
  • Tumor Suppressor Protein p53 / genetics*
  • Tumor Suppressor Protein p53 / physiology
  • Tumor Suppressor Proteins


  • CDKN1A protein, human
  • Cdkn1a protein, mouse
  • Cyclin-Dependent Kinase Inhibitor p21
  • Cyclins
  • DNA-Binding Proteins
  • Phosphoproteins
  • TP63 protein, human
  • Trans-Activators
  • Transcription Factors
  • Tumor Suppressor Protein p53
  • Tumor Suppressor Proteins

Associated data

  • GENBANK/AB016072
  • GENBANK/AB016073
  • PDB/P51A
  • PDB/P51B