Medical College of Wisconsin
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Characterization of a flatworm inositol (1,4,5) trisphosphate receptor (IP₃R) reveals a role in reproductive physiology. Cell Calcium 2013 May-Jun;53(5-6):307-14 PMID: 23481272 PMCID: PMC3665645


Inositol 1,4,5-trisphosphate receptors (IP₃Rs) are intracellular Ca²⁺ channels that elevate cytoplasmic Ca²⁺ in response to the second messenger IP3. Here, we describe the identification and in vivo functional characterization of the planarian IP₃R, the first intracellular Ca²⁺ channel to be defined in flatworms. A single IP₃R gene in Dugesia japonica encoded a 2666 amino acid protein (Dj.IP₃R) that shared well conserved structural features with vertebrate IP₃R counterparts. Expression of an NH₂-terminal Dj.IP₃R region (amino acid residues 223-585) recovered high affinity ³H-IP₃ binding (0.9±0.1 nM) which was abolished by a single point mutation of an arginine residue (R495L) important for IP₃ coordination. In situ hybridization revealed that Dj.IP₃R mRNA was most strongly expressed in the pharynx and optical nerve system as well as the reproductive system in sexualized planarians. Consistent with this observed tissue distribution, in vivo RNAi of Dj.IP₃R resulted in a decreased egg-laying behavior suggesting Dj.IP₃R plays an upstream role in planarian reproductive physiology.

Author List

Zhang D, Liu X, Chan JD, Marchant JS


Jonathan S. Marchant PhD Chair, Professor in the Cell Biology, Neurobiology and Anatomy department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Amino Acid Sequence
Cells, Cultured
Helminth Proteins
Inositol 1,4,5-Trisphosphate
Inositol 1,4,5-Trisphosphate Receptors
Molecular Sequence Data
Peptide Fragments
Protein Binding

View this publication's entry at the Pubmed website PMID: 23481272
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