Genomic organization of the glyceraldehyde-3-phosphate dehydrogenase gene family of Caenorhabditis elegans.
Glyceraldehyde-3-phosphate dehydrogenase (GAPDHase) is encoded by four genes designated gpd-1 through gpd-4 in the nematode Caenorhabditis elegans. gpd-1 has been isolated and sequenced, and is shown here to have a nearly identical copy (gpd-4) with respect to coding and regulatory flanking sequence information as well as to the placement of its two introns. Both genes, which are separated by 250,000 to 300,000 base-pairs were assigned to chromosome II by in situ hybridization and physically linked to a DNA polymorphism located near unc-4 on the genetic map. The genes gpd-2 and gpd-3 are also nearly identical with each other but differ from the gpd-1 and gpd-4 pair with respect to the positions of their two introns and a cluster of amino acid changes within the amino-terminal region of the enzyme. Furthermore, one gene from each pair (gpd-4 and gpd-2) exhibits a single amino acid substitution at positions heretofore known to be conserved in all other systems so far examined including the extreme thermophiles. gpd-2 and gpd-3 are organized as a direct tandem repeat separated by only 244 base-pairs. They have been assigned to an 85,200 base-pair contig that maps to the left end of the X chromosome. The absence of gpd-3 from C. elegans var. Bergerac was used as a marker to map the gpd-2,3 gene pair near unc-20. Northern analyses have shown that gpd-1 and gpd-4 are preferentially expressed in embryos, while the expression of gpd-2 and gpd-3 increases during postembryonic development. These analyses indicate that the gpd-1,4 gene pair encodes the minor isoenzyme, GAPDHase-1, present in all cells of the nematode while the other gene pair (gpd-2,3) encodes the major isoenzyme, GAPDHase-2, preferentially expressed in the bodywall muscle. The G + T-rich and T-rich regions essential for vertebrate beta-globin polyadenylation were also observed for gpd-3.
Huang
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XY
Department of Biochemical and Biophysical Sciences, University of Houston, Texas 77204-5500.
Barrios
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LA
Vonkhorporn
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P
Honda
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S
Albertson
D G
DG
Hecht
R M
RM
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002107:Caenorhabditis / Q000201:enzymology / Q000235:genetics*; D005796:Genes; D008040:Genetic Linkage; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000235:genetics*; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid
D005987:Glyceraldehyde-3-Phosphate Dehydrogenases