title: Rat inositol 1,4,5-trisphosphate receptor isoform 2 interacts with itself in its C-terminal portion and upstream of the first transmembrane domain.
abstract: In response to stimulation at the plasma membrane, hepatocellular Ca(2+) signals are fast and precise and lead to rapid local changes in cytoplasmic free Ca(2+) concentration. These changes result from the opening of the inositol 1,4,5-trisphosphate receptor (InsP(3)R), which is a four-subunit intracellular InsP(3)-gated channel that releases Ca(2+) from the stores. To investigate the molecular mechanism underlying interactions between the InsP(3)R subunits, we cloned the predominant hepatocellular isoform, InsP(3)R isoform 2 (InsP(3)R2), and screened for interactions using the yeast two-hybrid assay. We found that the C-terminal domain of rat InsP(3)R2 interacts with itself, and that the cytoplasmic part preceding the first transmembrane domain, a region near a Ca(2+)-binding site, also interacts with itself. These interactions were confirmed by pull-down experiments. The C-terminal domain of InsP(3)R2 is also able to interact with the C-termini of rat InsP(3)R1 and InsP(3)R3. These results advance our understanding of the molecular mechanisms that underlie the oligomerization and interactions of the InsP(3)R subunits during the opening/closing of the Ca(2+) channel.
authors.affiliation: Department of Clinical Pharmacology, University of Bern, Switzerland. .
authors.forename: F
authors.initials: F
authors.lastname: Magnino
authors.forename: K
authors.initials: K
authors.lastname: Schmidt
authors.forename: L
authors.initials: L
authors.lastname: Mery
authors.forename: J F
authors.initials: JF
authors.lastname: Dufour
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015220:Calcium Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D003001:Cloning, Molecular; D017931:DNA Primers; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D053496:Inositol 1,4,5-Trisphosphate Receptors; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D020798:Two-Hybrid System Techniques
chemical_list: D015220:Calcium Channels; D017931:DNA Primers; C506926:ITPR1 protein, human; D053496:Inositol 1,4,5-Trisphosphate Receptors; D020033:Protein Isoforms; D018160:Receptors, Cytoplasmic and Nuclear; D005982:Glutathione Transferase