Molecular imaging of protein-protein interactions in living animals

Refinement of the human genome is expected to facilitate investigations into normal physiology and disease processes, leading to discovery of targets for new medical therapies and drugs (1). However, regulation of gene expression, posttranslational modifications of proteins (e.g., phosphorylation or myristoylation), or interactions between proteins cannot be deduced or inferred from DNA sequences (2). Thus, a biological function has been assigned to only a small portion of the genome. The vast amount of available sequence data has produced a demand for tools to integrate these data into the complex physiology of whole organisms (3). To determine the function of a particular protein within its cellular context, researchers are developing and applying several different techniques for identifying and characterizing protein function and interactions in vivo.