The purpose of this Core is to provide advanced laser fluorescence microscopy instrumentation and expertise to all members of the Program Project. The Core houses two Argon ion lasers, two inverted microscopes with epi-fluorescence illumination (one of them currently on loan), and all optical and electronic interfaces to operate these instruments for TIRF and FLIC microscopy, as well as for FRAP and single molecule detection and tracking experiments. The day-to-day operation of the Core is headed by Dr. Volker Kiessling, a physicist who has many years of experience with the development and operation of advanced microscopy systems. The Core also includes for common access a new SPEX spectrofluorometer and a Bruker FTIR spectrometer with polarization and ATR capabilities. Visiting scientist from all three participating laboratories will be trained in the use of these instruments.