Cloning and expression of a Xenopus embryonic gap junction protein

Science. 1989 Mar 3;243(4895):1194-5. doi: 10.1126/science.2466337.


Gap junctions in the early amphibian embryo may play a fundamental role in the regulation of differentiation by mediating the cell-to-cell transfer of chemical signals. A complementary DNA encoding a gap junction present in Xenopus oocytes and early embryos has now been cloned and sequenced. This protein sequence is homologous to the well-characterized gap junction structural proteins rat connexin32 and connexin43. RNA blot analysis of total Xenopus oocyte RNA showed hybridization to a single 1.6-kilobase band. This messenger RNA is abundant in oocytes, decreases to levels below the sensitivity of our assay by stage 15 (18 hours), and is not detectable in RNA from a number of adult organs. To confirm that the oocyte cDNA encodes a gap junction channel, the protein was over expressed in Xenopus oocytes by injection of RNA synthesized in vitro. Pairs of RNA-injected oocytes formed many more time- and voltage-sensitive cell-cell channels than water-injected pairs.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Cell Communication
  • Cloning, Molecular*
  • Connexins
  • DNA Probes
  • Electric Conductivity
  • Female
  • Gene Expression Regulation
  • Intercellular Junctions / physiology
  • Membrane Proteins / genetics*
  • Membrane Proteins / physiology
  • Molecular Sequence Data
  • Nucleic Acid Hybridization
  • Oocytes / analysis
  • Oocytes / physiology
  • RNA / analysis
  • RNA, Messenger / analysis
  • Rats
  • Tissue Distribution
  • Xenopus / embryology*


  • Connexins
  • DNA Probes
  • Membrane Proteins
  • RNA, Messenger
  • RNA