Alternative splicing of a 51-nucleotide exon that encodes a putative protein kinase C phosphorylation site generates two forms of the chicken gamma-aminobutyric acidA receptor beta 2 subunit.
Complementary DNAs that encode two forms of the chicken gamma-aminobutyric acid type A (GABAA) receptor beta 2 subunit have been isolated. These polypeptides differ by the presence of (beta 2L) or absence (beta 2S) of 17 amino acids, which contain a possible target for phosphorylation by protein kinase C, in the large intracellular loop between the third and fourth membrane-spanning domains. The extra sequence in the chicken beta 2L subunit is not found in previously published GABAA receptor beta 2-subunit sequences. Analysis of genomic DNA has revealed that the two beta 2-subunit mRNAs arise by alternative splicing of a novel 51-nucleotide exon. Although the two beta 2-subunit transcripts appear to be present in 1-day-old chick brain at similar steady-state levels, we have been unable to detect an mRNA for the long form of the beta 2 subunit in either the bovine or the rat. Because the various GABAA receptor genes are thought to have arisen by duplication of a common ancestor, our data, taken together with that on the gamma 2 subunit, which occurs in two forms that arise by alternative splicing of a 24-nucleotide exons, suggest that the coding region of the primordial gene or one of its very early descendants contained 10 exons, not nine as previously thought.
Harvey
R J
RJ
Institut für Zellbiochemie und klinische Neurobiologie, Universitäts-Krankenhaus Eppendorf, Universität Hamburg, Germany.
Chinchetru
M A
MA
Darlison
M G
MG
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D001921:Brain / Q000378:metabolism; D002417:Cattle; D002645:Chickens / Q000235:genetics*; D017931:DNA Primers; D018076:DNA, Complementary / Q000378:metabolism; D005091:Exons; D007438:Introns; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D010766:Phosphorylation; D016133:Polymerase Chain Reaction; D011493:Protein Kinase C / Q000378:metabolism*; D012313:RNA / Q000302:isolation & purification; D051381:Rats; D011963:Receptors, GABA-A / Q000096:biosynthesis* / Q000235:genetics*; D017386:Sequence Homology, Amino Acid
D017931:DNA Primers; D018076:DNA, Complementary; D046911:Macromolecular Substances; D011963:Receptors, GABA-A; D012313:RNA; D011493:Protein Kinase C