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 at the plasma membrane of animal cells. They are localized in and required for the formation of several types of cell junctions, including epithelial tight and septate junctions as well as synaptic and neuromuscular junctions. They are also localized at the plasma membrane of other cell types, including erythrocytes, where they contribute to cell shape maintenance. MAGUKs function mainly by binding directly to the cytoplasmic termini of transmembrane proteins as well as to other signal transduction proteins. They appear to hold together elements of individual signaling pathways, thereby contributing to the efficiency and specificity of signaling interactions while simultaneously maintaining the structural specializations of the plasma membrane. BioEssays 1999;21:912-921.