Human cruciform binding protein belongs to the 14-3-3 family.
Cruciform DNA has been implicated in the initiation of DNA replication. Recently, we identified and purified from human (HeLa) cells a protein, CBP, with binding specificity for cruciform DNA. We have reported previously that the CBP activity sediments at approximately 66 kDa in a glycerol gradient. Here, photochemical cross-linking studies and Southwestern analyses confirm that a 70 kDa polypeptide interacts specifically with cruciform DNA. Microsequence analysis of tryptic peptides of the 70 kDa CBP reveals that it is 100% homologous to the 14-3-3 family of proteins and shows that CBP contains the epsilon, beta, gamma, and zeta isoforms of the 14-3-3 family. In addition to polypeptides with the characteristic molecular mass of 14-3-3 proteins (30 and 33 kDa), CBP also contains a polypeptide of 35 kDa which is recognized by an antibody specific for the epsilon isoform of 14-3-3. Cruciform-specific binding activity is also detected in 14-3-3 proteins purified from sheep brain. Immunofluorescene studies confirm the presence of the epsilon, beta, and zeta isoforms of 14-3-3 proteins in the nuclei of HeLa cells. The 14-3-3 family of proteins has been implicated in cell cycle control, and members of this family have been shown to interact with various signaling proteins. Cruciform binding is a new activity associated with the 14-3-3 family.
McGill Cancer Centre, McGill University, Montréal, Québec, Canada.
A
A
Todd
N
N
Cossons
A
A
Aitken
G B
GB
Price
M
M
Zannis-Hadjopoulos
D048948:14-3-3 Proteins; D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins; D001483:Base Sequence; D001923:Brain Chemistry; D002352:Carrier Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D002467:Cell Nucleus / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D007536:Isomerism; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation / Q000528:radiation effects; D010777:Photochemistry; D011506:Proteins / Q000737:chemistry* / Q000302:isolation & purification; D012756:Sheep; D014446:Tyrosine 3-Monooxygenase; D014466:Ultraviolet Rays
D048948:14-3-3 Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D011506:Proteins; C111062:chitin-binding protein 21, Serratia marcescens; D014446:Tyrosine 3-Monooxygenase