Diglons are heterodimeric proteins composed of IgLON subunits, and Diglon-CO inhibits neurite outgrowth from cerebellar granule cells.
IgLONs are a family of four cell adhesion molecules belonging to the Ig superfamily that are thought to play a role in cell-cell recognition and growth-cone migration. One member of the family, opioid-binding cell-adhesion molecule (OBCAM), might act as a tumour suppressor. Previous work has shown that limbic-system-associated protein (LAMP), CEPU-1/Neurotrimin and OBCAM interact homophilically and heterophilically within the family. Here, we show that, based on their relative affinities, CEPU-1 might be both a homo- and a heterophilic cell adhesion molecule, whereas LAMP and OBCAM act only as heterophilic cell adhesion molecules. A binding assay using recombinant IgLONs fused to human Fc showed that IgLONs are organized in the plane of the membrane as heterodimers, and we propose that IgLONs function predominantly as subunits of heterodimeric proteins (Diglons). Thus, the four IgLONs can form six Diglons. Furthermore, although singly transfected cell lines have little effect on neurite outgrowth, CHO cell lines expressing both CEPU-1 and OBCAM (Diglon-CO) inhibit neurite outgrowth from cerebellar granule cells.
Reed
James
J
Department of Human Anatomy and Cell Biology, Liverpool University, Sherrington Buildings, Ashton Street, Liverpool, L69 3GE, UK.
McNamee
Christine
C
Rackstraw
Stephen
S
Jenkins
John
J
Moss
Diana
D
D000818:Animals; D030161:Avian Proteins / Q000378:metabolism; D016466:CHO Cells; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000737:chemistry / Q000502:physiology*; D015816:Cell Adhesion Molecules, Neuronal / Q000502:physiology; D002460:Cell Line; D002465:Cell Movement; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology*; D002645:Chickens; D006224:Cricetinae; D019281:Dimerization; D004797:Enzyme-Linked Immunosorbent Assay; D058851:GPI-Linked Proteins; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007136:Immunoglobulins / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D019006:Neural Cell Adhesion Molecules / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D011485:Protein Binding; D011961:Receptors, Fc / Q000737:chemistry; D011994:Recombinant Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014162:Transfection
D030161:Avian Proteins; D015815:Cell Adhesion Molecules; D015816:Cell Adhesion Molecules, Neuronal; D058851:GPI-Linked Proteins; D007136:Immunoglobulins; D008562:Membrane Glycoproteins; D019006:Neural Cell Adhesion Molecules; C059785:OPCML protein, human; D011961:Receptors, Fc; D011994:Recombinant Proteins; C095362:limbic system-associated membrane protein; C102493:neural CEPU-1 protein, chicken; C092530:neurotrimin; D049452:Green Fluorescent Proteins