Disease relevance of Opcml

• Several lines of evidence using antibodies suggest that OBCAM may play a functional role in NG108-15 neuroblastoma x glioma cells, a useful model system that contains a homogeneous population of delta-opioid receptors [1].
• We previously reported that transfection of antisense OBCAM (opioid-binding cell adhesion molecule) cDNA into NG108-15 neuroblastoma x glioma hybrid cells, which contain delta-opioid receptors, results in greatly reduced opioid binding (Ann, D [2].

High impact information on Opcml

• OBCAM has a much more restricted distribution, being expressed at high levels principally in the cortical plate and hippocampus [3].
• Since this protein shows high sequence similarity to IgLON family members including LAMP, OBCAM, neurotrimin, CEPU-1, AvGP50, and GP55, we termed this protein Kilon (a kindred of IgLON) [4].
• Transfection of NG108-15 cells with antisense opioid-binding cell adhesion molecule cDNA alters opioid receptor-G-protein interaction [2].
• We have recently identified and sequenced the cDNA for an opioid-binding protein with homologies to cell adhesion molecules (OBCAM) (Schofield, P. R., McFarlard, K. C., Hayflick, J. S., Wilcox, J. N., Cho, T. M., Roy, S., Lee, N. M., Loh, H. H., and Seeburg, P. H. (1989) EMBO J. 8, 489-495) [1].
• We have previously found that OBCAM is localized preferentially to dendrites compared with somata and terminals of hypothalamic vasopressin-secreting magnocellular neurons [5].

Biological context of Opcml

• This localization indicates that OBCAM is one of the dendrite-associated cell adhesion molecules [5].
• Opioid-binding cell adhesion molecule (OBCAM)-related clones from a rat brain cDNA library [6].
• The largest clone, DUZ1, had a putative open reading frame (ORF) essentially identical to OBCAM in its C-terminal 318 amino acids (aa), but differing in its N-terminal aa (20 vs. 27 in OBCAM), and in all of its 5'-noncoding regions [6].
• Characterization and tissue distribution of opioid-binding cell adhesion molecule (OBCAM) using monoclonal antibodies [7].
• We have now completed the deduced amino acid sequence for two isoforms of chicken OBCAM and used recombinant LAMP, OBCAM and CEPU-1 to raise antisera specific to these three IgLONs [8].

Anatomical context of Opcml

• Electron microscopic observation using chromogen-intensified and gold-conjugated methods also demonstrated the OBCAM labeling at most of the neurosecretory granules within the dendrites, while the labeling within the somata was observed at only a few neurosecretory granules [5].
• A family of glycoproteins (GP55), which inhibit neurite outgrowth, are members of the Ig superfamily and are related to OBCAM, neurotrimin, LAMP and CEPU-1 [9].
• In contrast, opioid-binding cell adhesion molecule showed a regionally restricted expression pattern with high levels only in the cerebral cortex and hippocampus [10].
• Immunocytochemistry revealed Kilon and OBCAM immunoreactivity in the magnocellular neurons of the SON and PVN of the rat hypothalamus compared with outside of the SON and PVN in the hypothalamus [11].
• OBCAM was preferentially expressed in the central nervous system (CNS) and at a very low level in the spleen [12].

Associations of Opcml with chemical compounds

• During the postnatal development, OBCAM immunoreactivity targeted to vasopressin-positive dendrites became clear from at least 3 weeks after birth, although it appeared at only a few somata 2 weeks after birth [5].
• Extracellular immunoreactivity was eliminated with phosphatidylinositol-specific phospholipase C and this immunoreactivity resisted extraction with the nonionic detergent Triton X-100 at 4 degrees C, indicating that OBCAM is attached to the rafts via a glycosylphosphatidyl inositol anchor [13].

Other interactions of Opcml

• Opioid-binding cell adhesion molecule (OBCAM) is a member of the immunoglobulin superfamily containing limbic system-associated membrane protein (IgLON) subgroup of glycosylphosphatidylinositol-anchored immunoglobulin cell adhesion molecules [5].
• Expression of Kilon and opioid-binding cell adhesion molecule was increased gradually during postnatal development and maintained until adulthood [10].
• In the cerebellum, Kilon-immunoreactive puncta were observed to colocalize well with that of vesicle-associated membrane protein 2, while opioid-binding cell adhesion molecule immunoreactivity was observed only at part of synaptic glomeruli in the granular layer and rare in the molecular layer [10].
• Moreover, the immunoreactivity for OBCAM showed a punctate pattern in the dendrites similar to the immunostaining pattern of synapsin I [13].
• Morphologically, the distribution pattern of OBCAM immunoreactivity was very similar to that of synaptophysin, suggesting a role in the synaptic machinery [12].

Analytical, diagnostic and therapeutic context of Opcml

• Characterization of the expression of neurotrimin and OBCAM in the developing CNS by in situ hybridization reveals that these proteins are differentially expressed during development [3].
• Nested polymerase chain reaction using primers to the OBCAM sequence and internal primers to GP55 peptides produced two different polymerase chain reaction fragments with homology to OBCAM [9].
• Light microscopic immunohistochemistry demonstrated that the localization of opioid-binding cell adhesion molecule and Kilon coincided well with that of vesicle-associated membrane protein 2, a synaptic marker protein, in the cerebral cortex and hippocampus of adult brain [10].
• A binding analysis using a cross-linker and the immunoprecipitation technique demonstrated that Kilon and opioid-binding cell adhesion molecule interacted heterophilically and homophilically [10].
• Western blotting analysis revealed the specific expression of Kilon and OBCAM in the SON homogenates [11].

References