text: The InsP3 receptor was first purified from rat cerebellum by neuroscientists Surachai Supattapone and Solomon Snyder at Johns Hopkins University School of Medicine.
  The cDNA of the InsP3 receptor was first cloned in the laboratory of Katsuhiko Mikoshiba.  The initial sequencing was reported as an unknown protein enriched in the cerebellum called P400.  The large size of this open reading frame indicated a molecular weight similar to the protein purified biochemically, and soon thereafter it was confirmed that the protein p400 was in fact the inositol trisphosphate receptor.