  We report the cell biological applications of a recently developed
multiphoton fluorescence lifetime imaging microscopy system using a streak
camera (StreakFLIM). The system was calibrated with standard fluorophore
specimens and was shown to have high accuracy and reproducibility. We
demonstrate the applicability of this instrument in living cells for measuring
the effects of protein targeting and point mutations in the protein sequence
which are not obtainable in conventional intensity based fluorescence
microscopy methods. We discuss the relevance of such time resolved information
in quantitative energy transfer microscopy and in measurement of the parameters
characterizing intracellular physiology.

Cell Behavior