A novel protein with homology to the junctional adhesion molecule. Characterization of leukocyte interactions.
We have cloned a novel cDNA belonging to the Ig superfamily that shows 44% similarity to the junctional adhesion molecule (JAM) and maps to chromosome 21q21.2. The open reading frame of JAM2 predicts a 34-kDa type I integral membrane protein that features two Ig-like folds and three N-linked glycosylation sites in the extracellular domain. A single protein kinase C phosphorylation consensus site and a PDZ-binding motif are present in the short intracellular tail. Heterologous expression of JAM2 in Chinese hamster ovary cells defined a 48-kDa protein that localizes predominantly to the intercellular borders. Northern blot analysis showed that JAM2 is preferentially expressed in the heart. JAM2 homotypic interactions were demonstrated by the ability of JAM2-Fc to capture JAM2-expressing Chinese hamster ovary cells. We further showed that JAM2, but not JAM1, is capable of adhering to the HSB and HPB-ALL lymphocyte cell lines. Neutralizing mouse anti-JAM2 polyclonal antibodies provided evidence against homotypic interactions in this assay. Biotinylation of HSB cell membranes revealed a 43-kDa counter-receptor that precipitates specifically with JAM2-Fc. These characteristics of JAM2 led us to hypothesize a role for this novel protein in adhesion events associated with cardiac inflammatory conditions.
Cunningham
S A
SA
Department of Pharmacology, Texas Biotechnology Corporation, Houston, Texas 77030, USA. scunningham@tbc.com
Arrate
M P
MP
Rodriguez
J M
JM
Bjercke
R J
RJ
Vanderslice
P
P
Morris
A P
AP
Brock
T A
TA
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016466:CHO Cells; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules; D002874:Chromosome Mapping; D002891:Chromosomes, Human, Pair 21; D003001:Cloning, Molecular; D006224:Cricetinae; D018076:DNA, Complementary; D006801:Humans; D007136:Immunoglobulins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007962:Leukocytes / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D062765:Junctional Adhesion Molecule B
D015815:Cell Adhesion Molecules; D018076:DNA, Complementary; D007136:Immunoglobulins; D008565:Membrane Proteins; C411887:JAM2 protein, human; D062765:Junctional Adhesion Molecule B; C448000:JAM3 protein, human; C486723:Jam3 protein, mouse