Molecular cloning and functional co-expression of a Caenorhabditis elegans nicotinic acetylcholine receptor subunit (acr-2).
A number of putative nicotinic acetylcholine receptor subunit clones were isolated by screening a lambda library of Caenorhabditis elegans genomic DNA with a probe derived from the Drosophila melanogaster ard gene (a non-alpha nicotinic acetylcholine receptor subunit clone). Studies on one of these loci, acr-2, are described; acr-2 is located between sup-7 and unc-6 on the X chromosome. A full-length cDNA was isolated and sequenced. The cDNA encodes a putative non-alpha subunit of a nicotinic acetylcholine receptor that shows many of the conserved features of vertebrate and invertebrate non-alpha nicotinic acetylcholine receptor subunits. To investigate the functional expression of the subunit, the corresponding cRNA was produced, in vitro, and micro-injected into Xenopus oocytes. When expressed alone acr-2 shows no levamisole-gated channel activity. When co-expressed with a C. elegans alpha subunit (unc-38), which is itself unable to form functional homo-oligomers, acr-2 contributed to the formation of a functional channel. This is the first functional expression of a nematode nicotinic acetylcholine receptor and supports the interpretation that the differentiation between alpha and non-alpha subunits dates back to the earliest stages of the evolution of the metazoa.
Squire
M D
MD
Babraham Institute Laboratory of Molecular Signalling, Department of Zoology, University of Cambridge, UK.
Tornøe
C
C
Baylis
H A
HA
Fleming
J T
JT
Barnard
E A
EA
Sattelle
D B
DB
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017173:Caenorhabditis elegans / Q000235:genetics*; D029742:Caenorhabditis elegans Proteins; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D018076:DNA, Complementary; D006031:Glycosylation; D015801:Helminth Proteins / Q000235:genetics* / Q000378:metabolism; D015640:Ion Channel Gating; D007473:Ion Channels / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011978:Receptors, Nicotinic / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014981:Xenopus / Q000235:genetics
C098140:Acr-2 protein, C elegans; D029742:Caenorhabditis elegans Proteins; D018076:DNA, Complementary; D015801:Helminth Proteins; D007473:Ion Channels; D011978:Receptors, Nicotinic