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Characterization of the human LPIN1 ‐encoded phosphatidate phosphatase isoforms
Author(s) -
Han GilSoo,
Carman George M
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.694.8
Subject(s) - phosphatidate , heterologous expression , phosphatase , diacylglycerol kinase , dephosphorylation , biochemistry , enzyme , escherichia coli , gene isoform , chemistry , enzyme kinetics , microbiology and biotechnology , alternative splicing , isozyme , gene , biology , recombinant dna , active site , protein kinase c
The mammalian LPIN1 gene encodes the Mg 2+ ‐dependent phosphatidate (PA) phosphatase, which catalyzes the dephosphorylation of PA to produce diacylglycerol (DAG), and its expression by alternative splicing produces the α and β isoforms. Here, we found a novel splice form (γ) of human lipin 1, which differs from the α form by containing additional 26 amino acids. In addition, we characterized the enzymological properties of human LPIN1 α, β, and γ‐encoded PA phosphatases purified after heterologous expression in Escherichia coli . The LPIN1 ‐encoded PA phosphatase enzymes followed surface dilution kinetics with respect to PA using Triton X‐100/PA mixed micelles. These enzymes had similar K m values (4.2–4.5 mol %) for PA, but their V max values were in the order of α (34.9 μmol/min/mg) > β (24.9 μmol/min/mg) >> γ (3.4 μmol/min/mg). Although the lipin 1 isoforms showed a significant difference in catalytic activity, they were similar with respect to reaction conditions for optimum activity, inhibitors, and effectors. Supported by NIH grant GM‐28140.