Patent ID: 8772452

Claim:
A protein as defined by any one of (a) through (d) below: (a) a protein consisting of the amino acid sequence of SEQ ID NO: 2; (b) a protein consisting of the amino acid sequence of SEQ ID NO: 2 except that 1 to 3 amino acid(s), excluding amino acids at positions 107, 110, 120, 140, 179 and 180, are substituted with other amino acid(s), wherein the protein can bind to a peroxide of coelenterazine or a peroxide of a coelenterazine derivative to form a holoprotein that emits light in the presence of calcium ions; (c) a protein comprising the amino acid sequence of SEQ ID NO: 2, which can bind a peroxide of coelenterazine or a peroxide of a coelenterazine derivative to form a holoprotein that emits light in the presence of calcium ions; and, (d) a protein comprising the amino acid sequence of SEQ ID NO: 2 with 1 to 3 amino acid(s) except for the amino acid(s) at positions 107, 110, 120, 140, 179 and 180 being substituted with other amino acid(s), wherein the protein can bind to a peroxide of coelenterazine or a peroxide of a coelenterazine derivative to form a holoprotein that emits light in the presence of calcium ions.