Identification and characterization of cyclin X which activates transcriptional activities of c-Myc

Mol Biol Rep. 2009 Jan;36(1):97-103. doi: 10.1007/s11033-007-9156-5. Epub 2007 Dec 1.


Cyclins are eukaryotic proteins that play an active role in controlling cell division cycles and regulate cyclin dependent kinases (CDKs). In this study, we identified and characterized a new member of the human cyclin family. Its cDNA sequence contains an open reading frame of 864 bp, encoding a protein of 287 amino acids. This putative cyclin, designated cyclin X, contains a typical cyclin box. Cyclin X shows the highest sequence similarity in cyclin box to cyclin B3 and the similarity between these two proteins also extends to the whole molecule. The expression pattern of cyclin X showed that it was highly expressed in testis. Cyclin X protein was located in nucleus of the H1299 cells and Overexpression of cyclin X activated the transcriptional activities of c-Myc. These results indicate that cyclin X is a novel member of the human cyclin family and positive regulator of c-Myc-mediated gene transcription.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Cell Nucleus / metabolism
  • Cells, Cultured
  • Cyclin B / genetics
  • Cyclins / chemistry
  • Cyclins / genetics*
  • Cyclins / metabolism*
  • Gene Expression Regulation*
  • Genes, myc
  • Humans
  • Molecular Sequence Data
  • Proto-Oncogene Proteins c-myc / metabolism*
  • Sequence Alignment
  • Tissue Array Analysis
  • Transcriptional Activation*


  • CCNB3 protein, human
  • Cyclin B
  • Cyclins
  • MYC protein, human
  • Proto-Oncogene Proteins c-myc
  • cyclin X, human

Associated data

  • GENBANK/AF429969