February’s issue of Cold Spring Harbor Protocols contains a Topic Introduction on the subject of Photoactivation by Graham Ellis-Davies from Drexel University:

“Specific molecular interactions control cellular function. The photorelease of caged compounds (nucleotides, neurotransmitters, peptides, second messengers, proteins, etc.) can be used to control these interactions in living cells. Caged compounds are biological effector molecules whose active functionality has been chemically masked with a photoremovable protecting group. Illumination produces a concentration jump from the caged molecule. This article discusses the basic principles underlying photoactivation, the properties of caging chromophores and commercially available caged compounds, and practical considerations for their effective use.”

Our collection of protocols includes a wide variety of applications using photoactivation including the following:
Design, Synthesis, and Characterization of Caged Compounds
Introduction of Caged Peptide/Protein into Cells Using Microinjection
Introduction of Caged Peptide/Protein into Cells Using Bead Loading
Photoactivation-Based Labeling and In Vivo Tracking of RNA Molecules in the Nucleus
Inorganic Caged Compounds: Uncaging with Visible Light
Chemical Two-Photon Uncaging
Infrared-Guided Laser Stimulation of Neurons in Brain Slices
Photoactivation Cell Labeling for Cell Tracing in Avian Development