A comparison of internal eliminated sequences in the genes that encode two K(+)-channel isoforms in Paramecium tetraurelia

J Eukaryot Microbiol. Jul-Aug 1998;45(4):459-65. doi: 10.1111/j.1550-7408.1998.tb05100.x.


We examined both the somatic (macro-) and the germinal (micronuclear) DNAs that encode two K(+)-channel isoforms, PAK1 and PAK11, in Paramecium tetraurelia. The coding regions of these two isoforms are 88% identical in nucleotides and 95% identical in amino acids. Their introns are also highly conserved. Even some of the internal eliminated sequences in PAK1 and PAK11 are clearly related. PAK1 has five IESs; PAK11 has four. The first (5'-most) IESs of the two genes are located at the same site in the coding sequence but differ in size. The 2nd IES in PAK1 (206-bp), the largest among the nine IESs, has no PAK11 counterpart. The 3rd, 4th and 5th IESs in PAK1 have a counterpart in PAK11 that is similar in size and in sequence, and identical in its position in the coding sequence. In addition, the first IES of PAK11 bears some resemblance to the 4th one of PAK1. The similarities and differences between the two sets of IESs are discussed with respect to the origin and divergence of the two K(+)-channel isoforms.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • DNA, Protozoan
  • Genes, Protozoan*
  • Introns
  • Isomerism
  • Molecular Sequence Data
  • Paramecium tetraurelia / genetics*
  • Potassium Channels / genetics*
  • Protozoan Proteins / genetics*


  • DNA, Protozoan
  • PAK protein, Paramecium tetraurelia
  • Potassium Channels
  • Protozoan Proteins

Associated data

  • GENBANK/AF035270
  • GENBANK/AF035271
  • GENBANK/AF035272
  • GENBANK/AF035273
  • GENBANK/AF035274