CLMP, a Novel Member of the CTX Family and a New Component of Epithelial Tight Junctions

Abstract

The CTX family is a growing group of type I transmembrane proteins within the immunoglobulin superfamily (IgSF). They localize to junctional complexes between endothelial and epithelial cells and seem to participate in cell-cell adhesion and transmigration of leukocytes. Here, we report the identification of a new member of the CTX family. This protein, which was designated CLMP (coxsackie-and adenovirus receptor-like membrane protein), is composed of 373 amino acids including an extracellular part containing a V-and a C2-type domain, a transmembrane region and a cytoplasmic tail.

Tight junctions at a glance

“…Four JAMs -JAM-A, -B, -C and -D -have been identified, and all four can mediate homotypic cell-cell adhesion. Several of the JAM proteins, as well as the related proteins coxsackievirus and adenovirus receptor (CAR), CAR-like membrane protein (CLMP) and the endothelial-cellselective adhesion molecule (ESAM), associate with TJs and interact with adaptor proteins of the cytoplasmic plaque (Bazzoni et al, 2000;Ebnet et al, 2003;Ebnet et al, 2000;Raschperger et al, 2004;Wegmann et al, 2004). JAMs regulate adhesion between leukocytes and endothelial cells, as well as the paracellular transmigration of leukocytes across the endothelium, and have been shown to regulate the development of cell polarity by binding to the evolutionarily conserved complex between PAR3, PAR6 and atypical PKC (aPKC) (Bradfield et al, 2007;Ebnet et al, 2004;Weber et al, 2007).…”

Congenital short bowel syndrome as the presenting symptom in male patients with FLNA mutations

“…Raschperger et al 19 showed that CLMP co-localizes with actin filaments. They speculated that CLMP interacts with a protein that directly binds to actin filaments, which would bring CLMP to the tight junction by anchoring CLMP in the actin cytoskeleton.…”

Positive and negative regulation of adenovirus infection by CAR-like soluble protein, CLSP

“…15 We constructed a phylogenetic tree using amino-acid sequences of several vertebrate IgV domains in the CTX family. The results revealed that the closest relative to CLSP is CAR, followed by CLMP, 15 BT-IgSF 16 and ESAM.…”

“…15 We constructed a phylogenetic tree using amino-acid sequences of several vertebrate IgV domains in the CTX family. The results revealed that the closest relative to CLSP is CAR, followed by CLMP, 15 BT-IgSF 16 and ESAM. 17 Figure 8a shows a phylogenetic tree of the IgV domains of CAR and CLMP for the mouse, rat, human, bovine and chicken and three IgV domains of CLSP for the mouse and rat.…”

“…12,13 One of the characteristics of members of the Ig superfamily is sequence homology among the members. 14 For example, CAR is structurally similar to CAR-like membrane protein (CLMP), 15 brain-and testis-specific Ig superfamily (BT-IgSF), 16 and endothelial cell-selective adhesion molecule (ESAM). 17 Another characteristic is that many of the Ig-superfamily genes produce soluble receptors that lack the transmembrane and cytoplasmic domains of full-length receptors.…”