title: Secreted chick semaphorins bind recombinant neuropilin with similar affinities but bind different subsets of neurons in situ.
abstract: Collapsin-1, a member of the semaphorin family, activates receptors on specific growth cones, thereby inhibiting their motility. Neuropilin, a previously cloned transmembrane protein, has recently been identified as a candidate receptor for collapsin-1. We have completed the cloning of chick collapsin-3 and -5 and show that collapsin-1, -2, -3, and -5 bind to overlapping but distinct axon tracts. We infer that in situ, there are distinct receptors with different affinities for collapsin-1, -2, -3, and -5. In contrast, these four collapsins all bind recombinant neuropilin with similar affinities. Strong binding to neuropilin is mediated by the carboxy third of the collapsins, while the semaphorin domain confers their unique binding patterns in situ. We propose that neuropilin is a common component of a semaphorin receptor complex, and that additional differentially expressed receptor components interact with the semaphorin domains to confer binding specificity.
authors.affiliation: Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia 19104, USA.
authors.forename: L
authors.initials: L
authors.lastname: Feiner
authors.forename: A M
authors.initials: AM
authors.lastname: Koppel
authors.forename: H
authors.initials: H
authors.lastname: Kobayashi
authors.forename: J A
authors.initials: JA
authors.lastname: Raper
mesh_terms: D000818:Animals; D030161:Avian Proteins; D019556:COS Cells / Q000502:physiology; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D002645:Chickens; D003001:Cloning, Molecular; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D006023:Glycoproteins / Q000737:chemistry / Q000378:metabolism*; D036341:Intercellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins / Q000378:metabolism; D008969:Molecular Sequence Data; D009414:Nerve Growth Factors / Q000737:chemistry / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D039942:Neuropilin-1; D011485:Protein Binding / Q000502:physiology; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D040121:Semaphorin-3A; D039961:Semaphorins; D012680:Sensitivity and Specificity; D017386:Sequence Homology, Amino Acid; D013116:Spinal Cord / Q000737:chemistry / Q000196:embryology; D013477:Superior Colliculi / Q000737:chemistry / Q000196:embryology
chemical_list: D030161:Avian Proteins; D002352:Carrier Proteins; D006023:Glycoproteins; D036341:Intercellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D011994:Recombinant Proteins; C094536:SEMA3D protein, Gallus gallus; C108640:Semaphorin 3E, chicken; D040121:Semaphorin-3A; D039961:Semaphorins; D039942:Neuropilin-1