title: Cloning, embryonic expression, and functional characterization of two novel connexins from Xenopus laevis.
abstract: Vertebrate gap junctions are constituted of connexin (Cx) proteins. In Xenopus laevis, only seven different Cxs have been described so far. Here, we identify two new Cxs from X. laevis. Cx28.6 displays > 60% amino acid identity with human Cx25, Cx29 displays strong homology with mouse Cx26 and Cx30. Cx29 is expressed throughout embryonic development. Cx28.6 mRNA is only transiently found from stage 22 to 26 of development. While no Cx28.6 expression could be detected by whole mount in situ hybridization, expression of Cx29 was found in the developing endoderm, lateral mesoderm, liver anlage, pronephros, and proctodeum. Ectopic expression of Cx28.6 failed to produce functional gap-junctions. In contrast, ectopic expression of full-length Cx29 in HEK293 and COS-7 cells resulted in the formation of gap junction-like structures at the cell-cell interfaces. Ectopic expression of Cx29 in communication deficient N2A cell pairs led to functional electrical coupling.
authors.affiliation: Department of Medical Physiology, HLCU, University Medical Center Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands.
authors.forename: Teun P
authors.initials: TP
authors.lastname: de Boer
authors.forename: Bart
authors.initials: B
authors.lastname: Kok
authors.forename: Giulietta
authors.initials: G
authors.lastname: Roël
authors.forename: Toon A B
authors.initials: TA
authors.lastname: van Veen
authors.forename: Olivier H J
authors.initials: OH
authors.lastname: Destrée
authors.forename: Martin B
authors.initials: MB
authors.lastname: Rook
authors.forename: Marc A
authors.initials: MA
authors.lastname: Vos
authors.forename: Jacques M T
authors.initials: JM
authors.lastname: de Bakker
authors.forename: Marcel A G
authors.initials: MA
authors.lastname: van der Heyden
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D000072259:Connexin 26; D000075302:Connexin 30; D017630:Connexins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017629:Gap Junctions; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D008648:Mesoderm / Q000378:metabolism; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D029867:Xenopus Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D014982:Xenopus laevis / Q000378:metabolism*; D000097002:Gap Junction beta-1 Protein
chemical_list: D000072259:Connexin 26; D000075302:Connexin 30; D017630:Connexins; D029867:Xenopus Proteins; D000097002:Gap Junction beta-1 Protein; C000607045:GJB2 protein, Xenopus; C000607042:GJB2 protein, human; C514323:GJB7 protein, Xenopus