Skip to Content
MilliporeSigma
  • The MAGUK protein MPP7 binds to the polarity protein hDlg1 and facilitates epithelial tight junction formation.

The MAGUK protein MPP7 binds to the polarity protein hDlg1 and facilitates epithelial tight junction formation.

Molecular biology of the cell (2007-03-03)
Volker M Stucke, Evy Timmerman, Joel Vandekerckhove, Kris Gevaert, Alan Hall
ABSTRACT

Three groups of evolutionarily conserved proteins have been implicated in the establishment of epithelial cell polarity: the apically-localized proteins of the Par (Par3-Par6-aPKC-Cdc42) and Crumbs groups (Crb3-PALS1-PATJ) and the basolaterally localized proteins of the Dlg group (Dlg1-Scribble-Lgl). During epithelial morphogenesis, these proteins participate in a complex network of interdependent interactions that define the position and functional organization of adherens junctions and tight junctions. However, the biochemical pathways through which they control polarity are poorly understood. In this study, we identify an interaction between endogenous hDlg1 and MPP7, a previously uncharacterized MAGUK-p55 subfamily member. We find that MPP7 targets to the lateral surface of epithelial cells via its L27N domain, through an interaction with hDlg1. Loss of either hDlg1 or MPP7 from epithelial Caco-2 cells results in a significant defect in the assembly and maintenance of functional tight junctions. We conclude that the formation of a complex between hDlg1 and MPP7 promotes epithelial cell polarity and tight junction formation.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Monoclonal ANTI-FLAG® M2 antibody produced in mouse, clone M2, purified immunoglobulin (Purified IgG1 subclass), buffered aqueous solution (10 mM sodium phosphate, 150 mM NaCl, pH 7.4, containing 0.02% sodium azide)
Sigma-Aldrich
Anti-CASK Antibody, clone K56A, clone K56A, Chemicon®, from mouse
Sigma-Aldrich
Monoclonal Anti-α-Tubulin antibody produced in mouse, clone DM1A, ascites fluid