Abstract: Isolated nucleic acids encoding a fluorescent protein construct that detect apoptosis are disclosed. The isolated nucleic acids contain a donor-acceptor pair of green fluorescent proteins and a peptide linker containing a substrate sequence encoding a cleavage site of a caspase. The linker is flanked with at least one glycine pair. Expression constructs, isolated host cells and gene delivery vehicles containing these isolated nucleic acids are also disclosed.

Abstract: The present invention concerns fluorescent proteins modified such that said modified fluorescent protein incorporates a cleavage site for a protease, cleavage of said modified fluorescent protein at said cleavage site by said protease causing the alteration of at least one of the emission and excitation spectra of said modified fluorescent protein. In particular, the invention is concerned with using these modified fluorescent proteins as probes for detecting protease activity in living cells during the programmed cell death process (apoptosis). Also provided are nucleic acid sequence encoding same, recombinant DNA constructs expressing same, cells transformed or transfected with same, methods for detecting protease activity, and methods of detecting agents which affect protease activity, and kits for same.

Abstract: This invention provides a fluorescent protein construct to detect protease or caspase activated apoptosis. The construct contains a donor fluorescent protein; an acceptor fluorescent protein; and a linker peptide, wherein the linker peptide comprises a substrate sequence of a caspase. The linker peptide is position between the donor and acceptor proteins. This invention also provides nucleic acids encoding the fluorescent protein construct, expression constructs comprising the nucleic acids as well as gene delivery vehicles containing these nucleic acids.