title: Structural model and trans-interaction of the entire ectodomain of the olfactory cell adhesion molecule.
abstract: The ectodomain of olfactory cell adhesion molecule (OCAM/NCAM2/RNCAM) consists of five immunoglobulin (Ig) domains (IgI-V), followed by two fibronectin-type 3 (Fn3) domains (Fn3I-II). A complete structural model of the entire ectodomain of human OCAM has been assembled from crystal structures of six recombinant proteins corresponding to different regions of the ectodomain. The model is the longest experimentally based composite structural model of an entire IgCAM ectodomain. It displays an essentially linear arrangement of IgI-V, followed by bends between IgV and Fn3I and between Fn3I and Fn3II. Proteins containing IgI-IgII domains formed stable homodimers in solution and in crystals. Dimerization could be disrupted in vitro by mutations in the dimer interface region. In conjunction with the bent ectodomain conformation, which can position IgI-V parallel with the cell surface, the IgI-IgII dimerization enables OCAM-mediated trans-interactions with an intercellular distance of about 20 nm, which is consistent with that observed in synapses.
authors.affiliation: Protein Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, DK-2200 Copenhagen N, Denmark.
authors.forename: Nikolaj
authors.initials: N
authors.lastname: Kulahin
authors.forename: Ole
authors.initials: O
authors.lastname: Kristensen
authors.forename: Kim K
authors.initials: KK
authors.lastname: Rasmussen
authors.forename: Lars
authors.initials: L
authors.lastname: Olsen
authors.forename: Patrik
authors.initials: P
authors.lastname: Rydberg
authors.forename: Bente
authors.initials: B
authors.lastname: Vestergaard
authors.forename: Jette S
authors.initials: JS
authors.lastname: Kastrup
authors.forename: Vladimir
authors.initials: V
authors.lastname: Berezin
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Bock
authors.forename: Peter S
authors.initials: PS
authors.lastname: Walmod
authors.forename: Michael
authors.initials: M
authors.lastname: Gajhede
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002462:Cell Membrane / Q000378:metabolism; D018360:Crystallography, X-Ray; D019281:Dimerization; D005353:Fibronectins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D006801:Humans; D007136:Immunoglobulins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008961:Models, Structural; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D019006:Neural Cell Adhesion Molecules / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010843:Pichia; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism*; D013569:Synapses / Q000378:metabolism
chemical_list: D005353:Fibronectins; D007136:Immunoglobulins; D019006:Neural Cell Adhesion Molecules; D011994:Recombinant Proteins