Cloning of cDNAs encoding a cell-cycle-regulatory GTP-binding low-M(r) (GBLM) protein, Ran/TC4, from micronucleated Tetrahymena thermophila and amicronucleated Tetrahymena pyriformis

Gene. 1994 Jun 24;144(1):123-5. doi: 10.1016/0378-1119(94)90215-1.


Using PCR we have isolated two novel, closely related cDNA clones coding for a GTP-binding low-M(r) protein from Tetrahymena cells. The two clones from T. thermophila and T. pyriformis have open reading frames encoding proteins of 225 amino acids (aa) with a calculated M(r) of 25,648, and of 223 aa with a calculated M(r) of 25,421, respectively. The two gene products were very homologous to Ran/TC4 which are involved in chromatin condensation and control of the cell cycle: they possess much higher similarities to human, chicken, Schizosaccharomyces pombe and Dictyostelium discoideum Ran/TC4 homologues than those to other GTP-binding low-M(r) proteins, such as Ras and Rho. Thus, the two clones isolated from Tetrahymena were designated as Tt-ran and Tp-ran, respectively. Tt-ran and Tp-ran share 83% identity at nucleotide level, and about 92% identity and 94% homology at aa level. Tt- and Tp-Ran, as well as other Ran/TC4, contain the four consensus regions involved in GTP/GDP-binding and GTPase activities. However, at the C-terminal end, although all the known Ran/TC4 terminate in a consensus D-L motif, Tt-Ran and Tp-Ran do not have the unique aa sequence of other Ran/TC4, but have a F-N motif. Tt-ran and Tp-ran were actively transcribed in vivo as a 1.0-kb mRNA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Cell Cycle / genetics
  • Cloning, Molecular
  • DNA, Complementary
  • GTP-Binding Proteins / chemistry
  • GTP-Binding Proteins / genetics*
  • Micronucleus, Germline
  • Molecular Sequence Data
  • Protozoan Proteins / chemistry
  • Protozoan Proteins / genetics*
  • Sequence Homology, Amino Acid
  • Sequence Homology, Nucleic Acid
  • Tetrahymena pyriformis / genetics*
  • Tetrahymena pyriformis / ultrastructure
  • Tetrahymena thermophila / genetics*
  • Tetrahymena thermophila / ultrastructure


  • DNA, Complementary
  • Protozoan Proteins
  • GTP-Binding Proteins

Associated data

  • GENBANK/D17748
  • GENBANK/D21825