Patent ID: 7332598

Claim:
An isolated polynucleotide encoding at least a first monomer of a non-oligomerizing tandem fluorescent protein, said non-oligomerizing tandem fluorescent protein comprising a plurality of monomers, wherein the non-oligomerizing tandem fluorescent protein comprises a first monomer of an Aequorea green fluorescent protein (GFP; SEQ ID NO: 2) or a fluorescent protein of SEQ ID NO: 6 or SEQ ID NO: 10 operatively linked to at least a second monomer of the Aequorea GFP (SEQ ID NO: 2) or the fluorescent protein of SEQ ID NO: 6 or SEQ ID NO: 10, wherein said first monomer of the tandem fluorescent protein comprises a mutation substituting an amino acid having a positively charged side-chain for an amino acid residue corresponding to A206, L221, F223, or a combination thereof of SEQ ID NO: 2, SEQ ID NO: 6 or SEQ ID NO: 10, wherein the numbering of the amino acid residues conforms to that in native Aequorea GFP (SEQ ID NO: 2), and wherein the propensity of the tandem fluorescent protein to form intermolecular oligomers is reduced or inhibited as compared to a monomer of the Aequorea GFP (SEQ ID NO: 2) or the fluorescent protein of SEQ ID NO: 6 or SEQ ID NO: 10.