US Patent 7741270 Luminescent markers

The invention relates to luminescent proteins, nucleic acids encoding same, compositions and combinations comprising the proteins, and methods using the proteins, nucleic acids, compositions and combinations. In particular, a luminescent protein is provided comprising oncomodulin in which a salt bridge has been introduced to provide greater stability. The protein may be used as a luminescent marker in, for example, luminescent items, immunoassays, and fluorescent energy transfer assays.