RGD Reference Report - The cDNA cloning and characterization of inositol polyphosphate 4-phosphatase type II. Evidence for conserved alternative splicing in the 4-phosphatase family. - Rat Genome Database

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The cDNA cloning and characterization of inositol polyphosphate 4-phosphatase type II. Evidence for conserved alternative splicing in the 4-phosphatase family.

Authors: Norris, FA  Atkins, RC  Majerus, PW 
Citation: Norris FA, etal., J Biol Chem 1997 Sep 19;272(38):23859-64.
RGD ID: 633135
Pubmed: (View Article at PubMed) PMID:9295334

Inositol polyphosphate 4-phosphatase (4-phosphatase) is a Mg2+-independent enzyme that catalyzes the hydrolysis of the 4-position phosphate of phosphatidylinositol 3,4-bisphosphate, inositol 1,3,4-trisphosphate, and inositol 3,4-bisphosphate. We have isolated cDNA encoding a 105,257-Da protein that is 37% identical to the previously cloned 4-phosphatase. Recombinant protein was expressed in Escherichia coli and shown to hydrolyze all three 4-phosphatase substrates with enzymatic properties similar to the original enzyme. We designate the original 4-phosphatase and the new isozyme as inositol polyphosphate 4-phosphatase types I and II, respectively. 4-Phosphatase II is highly conserved with the human and rat enzymes having 90% amino acid identity. A conserved motif between 4-phosphatase I and II is the sequence CKSAKDRT that contains the Cys-Xaa5-Arg active site consensus sequence identified for other Mg2+-independent phosphatases. Northern blot analysis indicated that 4-phosphatase II is widely expressed with the highest levels occurring in the skeletal muscle and heart. In addition, cDNA encoding alternatively spliced forms of human 4-phosphatase I (107, 309 Da) and rat 4-phosphatase II (106,497 Da) were also isolated that encode proteins with a putative transmembrane domain near their C termini. These alternatively spliced forms were expressed as recombinant proteins in E. coli and SF9 insect cells and found to possess no detectable enzymatic activity suggesting that additional factors and/or processing may be required for these alternatively spliced isozymes.



Gene Ontology Annotations    

Biological Process

Molecular Function

Objects Annotated

Genes (Rattus norvegicus)
Inpp4b  (inositol polyphosphate-4-phosphatase type II B)

Objects referenced in this article
Gene INPP4A inositol polyphosphate-4-phosphatase type I A Homo sapiens
Gene INPP4B inositol polyphosphate-4-phosphatase type II B Homo sapiens

Additional Information