Cloning and expression of a Xenopus embryonic gap junction protein.
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.
Ebihara
L
L
Department of Pharmacology, Columbia University, New York, NY 10032.
Beyer
E C
EC
Swenson
K I
KI
Paul
D L
DL
Goodenough
D A
DA
D000595:Amino Acid Sequence; D000818:Animals; D002450:Cell Communication; D003001:Cloning, Molecular; D017630:Connexins; D015342:DNA Probes; D004553:Electric Conductivity; D005260:Female; D005786:Gene Expression Regulation; D007365:Intercellular Junctions / Q000502:physiology; D008565:Membrane Proteins / Q000235:genetics* / Q000502:physiology; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D009865:Oocytes / Q000032:analysis / Q000502:physiology; D012313:RNA / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D014018:Tissue Distribution; D014981:Xenopus / Q000196:embryology*
D017630:Connexins; D015342:DNA Probes; D008565:Membrane Proteins; D012333:RNA, Messenger; D012313:RNA