Tight junctions (zonulae occludens) are critical to the maintenance of cell polarity and intracellular barriers between epithelial and endothelial cells. Protein components of the tight junctions include actin filaments, symplekin, occludin, Rab3B, AF-6, 7H6, ZO-1, and ZO-2. Analysis of ZO-1 and -2 resulted in their inclusion in the MAGUK protein family. This family also includes the discs large tumor suppressor protein (Dlg-A) of Drosophila; p55, an erythrocyte membrane protein; and PSD-95/SAP90, a synaptic membrane protein. All family members contain a region homologous to guanylate kinase (GuK), a src homology (SH3) domain, and multiple PDZ domains. Through these elements, MAGUK proteins function in signal transduction and, possibly, tumor suppression. ZO-1 is a peripheral membrane phosphoprotein that binds to other tight junction proteins such as occludin and AF-6. Via its SH3 domain, ZO-1 interacts with a serine protein kinase that phosphorylates a region immediately C-terminal of the SH3 domain. Taken together, these data indicate that ZO-1 is a critical element in the formation of tight junctions and may also serve an important role in signaling and tumor suppression.
This antibody is routinely tested by western blot analysis. Other applications were tested at BD Biosciences Pharmingen during antibody development only or reported in the literature.