POLARIZED SIGNALING - BASOLATERAL RECEPTOR LOCALIZATION IN EPITHELIAL-CELLS BY PDZ-CONTAINING PROTEINS

Extracellular signals are normally presented to one surface of epithel ial cells and to one end of neurons, and so neuronal and epithelial ce ll signaling is inherently polarized. Another aspect of signaling pola rity is that receptors are often asymmetrically distributed on the sur faces of polarized cells, Recent evidence from studies of Caenorhabdit is elegans shows that signaling polarity plays an important role in de velopment. The underlying mesoderm induces the overlying ectoderm to f orm the vulva, and asymmetric distribution of the signal receptor on t he basolateral surface of the epithelium is crucial for this signaling . In neurons, the localization of neurotransmitter receptors and ion c hannels at synapses allows neurons to be exquisitely sensitive to syna ptic inputs. Exciting recent reports suggest that receptor localizatio n to neuronal synapses and the basolateral membrane domains of epithel ia may involve a common molecular mechanism involving localization by PDZ-containing proteins.