Heterooligomer of type 1 and type 2 inositol 1, 4, 5-trisphosphate receptor expressed in rat liver membrane fraction exists as tetrameric complex.
Functional IP(3)-sensitive intracellular Ca(2+) release channel is considered to be a tetramer of IP(3)R. Heterooligomeric complexes composed of distinct types of IP(3)R have been reported, however, crucial evidences for them being tetramer have not appeared. Here we report that the heterooligomer composed of IP(3)R1 and IP(3)R2 also exists as tetramer. Cross-linked heterooligomer was immunoprecipitated with IP(3)R1-specific antibody and detected by agarose-PAGE/Western blot analysis with IP(3)R2-specific antibody. Tetramer, trimer, dimer, and possibly monomer were detected. The trimer, dimer, and monomer were likely to be originated from the tetramer, since: (1) the immunoprecipitating antibody (IP(3)R1-specific) does not recognize IP(3)R2, therefore IP(3)R2 monomer itself could not have been immunoprecipitated; and (2) tetramer was the major native product of IP(3)R complex containing type 2 isoform in liver membrane fraction. Thus we conclude tetramer is the native form of heterooligomer composed of IP(3)R1 and IP(3)R2.
Onoue
H
H
Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka, 812-8582, Japan. onouehit@pharmaco.med.kyushu-u.ac.jp
Tanaka
H
H
Tanaka
K
K
Doira
N
N
Ito
Y
Y
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D015153:Blotting, Western; D015220:Calcium Channels / Q000096:biosynthesis* / Q000737:chemistry* / Q000302:isolation & purification; D002462:Cell Membrane / Q000378:metabolism; D002531:Cerebellum / Q000378:metabolism; D003432:Cross-Linking Reagents; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D053496:Inositol 1,4,5-Trisphosphate Receptors; D008099:Liver / Q000378:metabolism*; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000276:immunology; D055503:Protein Multimerization; D051381:Rats; D017208:Rats, Wistar; D018160:Receptors, Cytoplasmic and Nuclear / Q000096:biosynthesis* / Q000737:chemistry* / Q000302:isolation & purification
D000906:Antibodies; D015220:Calcium Channels; D003432:Cross-Linking Reagents; C506926:ITPR1 protein, human; C506927:ITPR2 protein, human; D053496:Inositol 1,4,5-Trisphosphate Receptors; D046911:Macromolecular Substances; D010446:Peptide Fragments; D018160:Receptors, Cytoplasmic and Nuclear; D015544:Inositol 1,4,5-Trisphosphate