Signaling pathways are focused at specialized regions of the plasma membrane by scaffolding proteins of the MAGUK family

The MAGUKs (membrane-associated guanylate kinase homologs) are a family of proteins that act as molecular scaffolds for signaling pathway components a t the plasma membrane of animal cells. They are localized in and required f or the formation of several types of cell junctions, including epithelial t ight and septate junctions as well as synaptic and neuromuscular junctions. They are also localized at the plasma membrane of other cell types, includ ing erythrocytes, where they contribute to cell shape maintenance. MAGUKs f unction mainly by binding directly to the cytoplasmic termini of transmembr ane proteins as well as to other signal transduction proteins. They appear to hold together elements of individual signaling pathways, thereby contrib uting to the efficiency and specificity of signaling interactions while sim ultaneously maintaining the structural specializations of the plasma membra ne. BioEssays 1999;21:912-921, (C) 1999 John Wiley & Sons, Inc.