title: Junctional adhesion molecule interacts with the PDZ domain-containing proteins AF-6 and ZO-1.
abstract: We have identified the PDZ domain protein AF-6 as an intracellular binding partner of the junctional adhesion molecule (JAM), an integral membrane protein located at cell contacts. Binding of AF-6 to JAM required the presence of the intact C terminus of JAM, which represents a classical type II PDZ domain-binding motif. Although JAM did not interact with the single PDZ domains of ZO-1 or of CASK, we found that a ZO-1 fragment containing PDZ domains 2 and 3 bound to JAM in vitro in a PDZ domain-dependent manner. AF-6 as well as ZO-1 could be coprecipitated with JAM from endothelial cell extracts, demonstrating the association of the endogenously expressed molecules in vivo. Targeting of JAM to sites of cell contacts could be affected by the loss of the PDZ domain-binding C terminus. Full-length mouse JAM co-distributed with endogenous AF-6 in human Caco-2 cells at sites of cell contact independent of whether adjacent cells expressed mouse JAM as an extracellular binding partner. In contrast, truncated JAM lacking the PDZ domain-binding C terminus did not co-distribute with endogenous AF-6, but was restricted to cell contacts between cells expressing mouse JAM. Our results suggest that JAM can be recruited to intercellular junctions by its interaction with the PDZ domain-containing proteins AF-6 and possibly ZO-1.
authors.affiliation: Institute of Cell Biology, ZMBE, University of Muenster, D-48149 Muenster, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Ebnet
authors.forename: C U
authors.initials: CU
authors.lastname: Schulz
authors.forename: M K
authors.initials: MK
authors.lastname: Meyer Zu Brickwedde
authors.forename: G G
authors.initials: GG
authors.lastname: Pendl
authors.forename: D
authors.initials: D
authors.lastname: Vestweber
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D001665:Binding Sites; D002196:Capillaries; D015815:Cell Adhesion Molecules / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002560:Cerebrovascular Circulation; D003001:Cloning, Molecular; D004730:Endothelium, Vascular / Q000502:physiology; D006801:Humans; D062726:Junctional Adhesion Molecules; D016547:Kinesins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009218:Myosins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019108:Tight Junctions / Q000502:physiology*; D014162:Transfection; D062826:Zonula Occludens-1 Protein; D018631:ras Proteins / Q000378:metabolism
chemical_list: C095516:AFDN protein, human; C490657:Afdn protein, mouse; D000906:Antibodies; D015815:Cell Adhesion Molecules; D062726:Junctional Adhesion Molecules; D008565:Membrane Proteins; D010750:Phosphoproteins; D011994:Recombinant Proteins; C569042:TJP1 protein, human; C569043:Tjp1 protein, mouse; D062826:Zonula Occludens-1 Protein; D009218:Myosins; D016547:Kinesins; D018631:ras Proteins