PDZ domains: fundamental building blocks in the organization of protein complexes at the plasma membrane

PDZ domains have recently emerged as central organizers of protein complexes at the plasma membrane. Although new information about PDZ domains appears at a bewildering rate, we will attempt to distill a few general concepts that have emerged about their biology. These include the structural basis for specificity of their binding interactions and ideas about how they organize both small local protein complexes used for signal transduction (transducisomes) and larger two-dimensional complexes like cell junctions and plasma membrane domains.