More on target with protein phosphorylation: Conferring specificity by location

One important regulatory mechanism in the control of phosphorylation events is the subcellular location of phosphatases or kinases. Several serine/threonine phosphatases and kinases have now been shown to be associated with targeting subunits; these contribute to the organization and specificity of signal transduction pathways by favoring the accessibility of their enzymes to certain substrates.