Related Experiment Video

Updated: Aug 10, 2026

Analysis of Protein-protein Interactions and Co-localization Between Components of Gap, Tight, and Adherens Junctions in Murine Mammary Glands
11:31

Analysis of Protein-protein Interactions and Co-localization Between Components of Gap, Tight, and Adherens Junctions in Murine Mammary Glands

Published on: May 30, 2017

JAM4, a junctional cell adhesion molecule interacting with a tight junction protein, MAGI-1

Susumu Hirabayashi1, Makiko Tajima, Ikuko Yao

  • 1Department of Medical Biochemistry, Graduate School of Medicine, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo 113-8519, Japan.

Molecular and Cellular Biology
|May 30, 2003
PubMed

Insights

Junctional adhesion molecule 4 (JAM4) interacts with MAGI-1, forming a novel protein complex at tight junctions. This JAM4-MAGI-1 complex enhances cell adhesion and regulates epithelial barrier function.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • MAGI-1 is a scaffold protein at epithelial tight junctions.
  • Understanding proteins at tight junctions is crucial for epithelial barrier function.

Purpose of the Study:

  • To identify novel MAGI-1 binding proteins.
  • To characterize the function of JAM4 in epithelial cells.

Main Methods:

  • Co-immunoprecipitation assays to detect protein interactions.
  • Immunofluorescence microscopy to determine protein localization.
  • Cell adhesion and permeability assays in cultured cells.

Main Results:

  • JAM4 was identified as a novel MAGI-1 binding protein.
  • JAM4 mediates calcium-independent homophilic adhesion.
  • The JAM4-MAGI-1 complex enhances cell adhesion and reduces epithelial permeability.

Conclusions:

  • JAM4 and MAGI-1 form a functional complex at tight junctions.
  • This complex plays a role in regulating epithelial barrier integrity.
  • The JAM4-MAGI-1 machinery may be important for kidney glomerulus and intestinal epithelial cell function.

More Related Videos

The C. elegans Intestine As a Model for Intercellular Lumen Morphogenesis and In Vivo Polarized Membrane Biogenesis at the Single-cell Level: Labeling by Antibody Staining, RNAi Loss-of-function Analysis and Imaging12:15

The C. elegans Intestine As a Model for Intercellular Lumen Morphogenesis and In Vivo Polarized Membrane Biogenesis at the Single-cell Level: Labeling by Antibody Staining, RNAi Loss-of-function Analysis and Imaging

Published on: October 3, 2017

Immunostaining and Dye Penetration Experiments to Define Core Pleated Septate Junction Proteins in Drosophila Embryonic Epithelia09:37

Immunostaining and Dye Penetration Experiments to Define Core Pleated Septate Junction Proteins in Drosophila Embryonic Epithelia

Published on: February 27, 2026

Related Concept Videos

Anchoring Junctions01:03

Anchoring Junctions

Anchoring junctions are multiprotein complexes that help cells connect to other cells and the extracellular matrix. Anchoring junctions are present on the lateral and basal surfaces of cells, providing strong and flexible connections. Focal adhesions are often formed due to cell interactions with the ECM substrata, which initiate signal transduction via kinase cascades and other mechanisms. Together, they provide stability and tissue integrity. There are three types of anchoring junctions:...
Overview of Cell-Cell Junctions01:14

Overview of Cell-Cell Junctions

The complex three-dimensional arrangement of cells in any multicellular organism is defined and maintained by interactions of cells with each other and the extracellular matrix. Cell-cell junctions are specialized structures where the multi-protein complexes on one cell interact with the multi-protein complexes on another  cell. These cell junctions are classified  into three main types based on their function — occluding, anchoring, and gap junctions.
Occluding or Tight Junctions
Tight...
Adherens Junctions01:24

Adherens Junctions

Strong contact points between adjacent cells anchor them to each other, forming tissues. Such anchoring junctions are of two types –  adherens junctions and desmosomes. Adherens junctions are abundant in tissues such as  epithelium and endothelium, forming a continuous zone of adhesion called the adhesion belt. In other tissues, such as  heart muscle, they appear as clusters, linking the cells to produce coordinated heart muscle contraction.
Adherens Junctions are Dynamic
The endothelial cells...
Tight Junctions01:29

Tight Junctions

Tight junctions are molecular seals between cells that prevent the leaking of fluids, ions, and other small solutes across cavities and compartments in multicellular organisms. They are mainly composed of claudin and occludin transmembrane proteins, and other proteins such as tricellulin and JAM (junctional adhesion molecule). All these proteins are 4-pass transmembrane proteins, except JAM, which is a single-pass transmembrane protein belonging to the immunoglobulin superfamily. The...
Immunoglobulin-like Cell Adhesion Molecules01:31

Immunoglobulin-like Cell Adhesion Molecules

Immunoglobulin-like cell adhesion molecules or Ig-CAMs are a versatile group of cell surface glycoproteins belonging to the immunoglobulin protein superfamily. Ig-CAMs possess the characteristic immunoglobulin protein domains and other domains such as the fibronectin type III domain. The Ig domains are glycosylated to varying degrees in different Ig-CAMs.
Ig-CAMs exhibit either homophilic binding (to other Ig-CAMs) or heterophilic binding (to other ligands such as integrins). While most Ig-CAMs...
Overview of Cell-Cell Junctions01:14

Overview of Cell-Cell Junctions

The complex three-dimensional arrangement of cells in any multicellular organism is defined and maintained by interactions of cells with each other and the extracellular matrix. Cell-cell junctions are specialized structures where the multi-protein complexes on one cell interact with the multi-protein complexes on another  cell. These cell junctions are classified  into three main types based on their function — occluding, anchoring, and gap junctions.
Occluding or Tight Junctions
Tight...