CD300 antigen like family member G: A novel Ig receptor like protein exclusively expressed on capillary endothelium.
We report the characteristics of CD300LG, a member of the CD300 antigen like family. Its genomic structure is similar in both mouse and human, and at least four isoforms exist in both species. The amino acid sequence of the immunoglobulin (Ig) V like domain of CD300LG showed approximately 35% identity to those of the polymeric Ig receptor (pIgR) and Fcalpha/muR. Interestingly, mouse CD300LG proteins were uniquely expressed on capillary endothelium. Immunoelectron microscopy revealed that mouse CD300LG is localized on both apical and basolateral plasma membranes, as well as on intracellular vesicular structures, in the capillary endothelium. Transcytosis assays using polarized MDCK epithelial cells showed that CD300LG could be transcytosed bidirectionally. Furthermore, CD300LG exogenously expressed on HeLa cells could take up IgA2 and IgM, but not IgG. These results suggest that CD300LG might play an important role in molecular traffic across the capillary endothelium.
Takatsu
Hiroyuki
H
Laboratory for Epithelial Immunobiology, Research Center for Allergy and Immunology, RIKEN, Yokohama 230-0045, Japan.
Hase
Koji
K
Ohmae
Masumi
M
Ohshima
Sayaka
S
Hashimoto
Koji
K
Taniura
Naoko
N
Yamamoto
Akitsugu
A
Ohno
Hiroshi
H
D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D000954:Antigens, Surface / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D042783:Endothelial Cells / Q000276:immunology / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007150:Immunohistochemistry; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009928:Organ Specificity; D011971:Receptors, Immunologic / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D054340:Receptors, KIR; D016415:Sequence Alignment
D015703:Antigens, CD; D000954:Antigens, Surface; C444139:CD300C protein, human; C584286:CD300LG protein, human; C515071:Cd300lg protein, mouse; D008562:Membrane Glycoproteins; D011971:Receptors, Immunologic; D054340:Receptors, KIR