ABSTRACT
In recent years, it has become well recognized that eukaryotic cells utilize protein-protein interactions for a number of
cellular processes, such as assembly of the cytoskeleton,
transference of signals during signal transduction, and to compartmentalize proteins. Protein interaction modules often
serve to mediate these protein-protein interactions, and have the following properties: they are typically 60-140 amino
acids in length, fold autonomously within the context of the protein that contains the module, and bind short (i.e., 4-7
amino acids) segments of other proteins. Examples include the Eps15 homology (EH) domain, the phosphotyrosine bind-
ing domain (PTB), the postsynaptic density=disc-large=ZO1 (PDZ) domain, the Src homology (SH) 2 and 3 domains, and
the WW domain (Fig. 1).
