title: Structural features of collapsin required for biological activity and distribution of binding sites in the developing chick.
abstract: We have used Fc-chimeras of collapsin-1/Sema III to study the structure-function activity of this recently identified repulsive axonal guidance molecule and to map the distribution of its binding sites during chick development. Our results show that the biological activity of the collapsin-Fc in an in vitro collapse assay is independent of both the Ig-domain and the positive charged carboxy terminus. Collapsin binding sites were found on a number of neuronal fiber tracts, and in two instances (DRG tracts and the retinotectal projection) this expression is both highly dynamic and consistent with them playing a role in axonal growth and guidance. Collapsin-1 binding sites were also found on a number of nonneuronal structures that do not produce collapsin-1 mRNA. We postulate that these sites may act to localize or concentrate collapsin-1 released from growing axons and in this way allow for an autocrine axonal guidance mechanism to function during development.
authors.affiliation: Department of Experimental Pathology, UMDS, Guy's Hospital Medical School, London, United Kingdom.
authors.forename: B J
authors.initials: BJ
authors.lastname: Eickholt
authors.forename: R
authors.initials: R
authors.lastname: Morrow
authors.forename: F S
authors.initials: FS
authors.lastname: Walsh
authors.forename: P
authors.initials: P
authors.lastname: Doherty
mesh_terms: D000818:Animals; D001665:Binding Sites; D002642:Chick Embryo; D006023:Glycoproteins / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology*; D007141:Immunoglobulin Fc Fragments / Q000235:genetics / Q000494:pharmacology; D007797:Laminin / Q000378:metabolism; D009414:Nerve Growth Factors / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology*; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism / Q000494:pharmacology; D040121:Semaphorin-3A; D013116:Spinal Cord / Q000254:growth & development / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D006023:Glycoproteins; D007141:Immunoglobulin Fc Fragments; D007797:Laminin; D009414:Nerve Growth Factors; D011993:Recombinant Fusion Proteins; D040121:Semaphorin-3A