Characterization of two genes, Impa1 and Impa2 encoding mouse myo-inositol monophosphatases.
The enzyme myo-inositol monophosphatase (Impa) catalyzes the synthesis of free myo-inositol from various myo-inositol monophosphates in the phosphatidylinositol signaling system. Impa is a lithium-blockable enzyme that has been hypothesized to be the biological target for lithium-salts used as mood-stabilizing drugs in the treatment of manic-depressive (bipolar) illness. As an initial step to explore the functional consequences of reduced or absent Impa activity in an animal model we here report the isolation of two Impa-encoding mouse genes, Impa1 and Impa2. Impa1 spans approximately 17.5 kb and contains nine exons of 46--1354 bp encoding a protein of 277 amino acids. Impa2 spans at least 19.5 kb and contains eight exons of 46--444 bp size encoding a protein of 290 amino acids. The genomic structure including the positions of the exon-intron splice sites seems to be conserved among myo-inositol monophosphatase genes in mammalian species. One or more Impa-like genes do also exist in evolutionary more distant species like invertebrates, plants and bacteria. The proteins encoded by the non-vertebrate genes seem to be equally related to Impa1 and Impa2. We therefore suggest that the Impa1 and Impa2 genes duplicated from a common ancestral gene after the evolutionary divergence of vertebrates.
Shamir
A
A
Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva, Israel.
Sjøholt
G
G
Ebstein
R P
RP
Agam
G
G
Steen
V M
VM
D000818:Animals; D001483:Base Sequence; D004247:DNA / Q000737:chemistry / Q000235:genetics; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D005057:Eukaryotic Cells / Q000201:enzymology; D005091:Exons; D005796:Genes / Q000235:genetics*; D006801:Humans; D007438:Introns; D051379:Mice; D008969:Molecular Sequence Data; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics*; D011387:Prokaryotic Cells / Q000201:enzymology; D017422:Sequence Analysis, DNA; D013045:Species Specificity
D018076:DNA, Complementary; D004247:DNA; D010744:Phosphoric Monoester Hydrolases; C021822:myo-inositol-1 (or 4)-monophosphatase