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Mol Biol Cell. 2000 Jul;11(7):2459-70.

Two Drosophila innexins are expressed in overlapping domains and cooperate to form gap-junction channels.

Author information

1
Sussex Centre for Neuroscience, School of Biological Sciences, University of Sussex, Brighton, BN1 9QG, United Kingdom. l.a.stebbings@sussex.ac.uk

Abstract

Members of the innexin protein family are structural components of invertebrate gap junctions and are analogous to vertebrate connexins. Here we investigate two Drosophila innexin genes, Dm-inx2 and Dm-inx3 and show that they are expressed in overlapping domains throughout embryogenesis, most notably in epidermal cells bordering each segment. We also explore the gap-junction-forming capabilities of the encoded proteins. In paired Xenopus oocytes, the injection of Dm-inx2 mRNA results in the formation of voltage-sensitive channels in only approximately 40% of cell pairs. In contrast, Dm-Inx3 never forms channels. Crucially, when both mRNAs are coexpressed, functional channels are formed reliably, and the electrophysiological properties of these channels distinguish them from those formed by Dm-Inx2 alone. We relate these in vitro data to in vivo studies. Ectopic expression of Dm-inx2 in vivo has limited effects on the viability of Drosophila, and animals ectopically expressing Dm-inx3 are unaffected. However, ectopic expression of both transcripts together severely reduces viability, presumably because of the formation of inappropriate gap junctions. We conclude that Dm-Inx2 and Dm-Inx3, which are expressed in overlapping domains during embryogenesis, can form oligomeric gap-junction channels.

PMID:
10888681
PMCID:
PMC14932
DOI:
10.1091/mbc.11.7.2459
[Indexed for MEDLINE]
Free PMC Article

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