Neuromusculin, a Drosophila gene expressed in peripheral neuronal precursors and muscles, encodes a cell adhesion molecule.
To unravel the molecular mechanisms of peripheral nervous system differentiation in Drosophila, we have screened for and identified genes that are expressed in sensory mother cells. Here, we describe a novel gene, neuromusculin (nrm), that is expressed in sensory mother cells and developing muscles. nrm encodes a member of the immunoglobulin superfamily. Immunoblots of Schneider 2 cells transfected with an nrm cDNA indicate that Nrm is present in a membrane-associated form and a secreted form. Cell aggregation assays suggest that Nrm is a homophilic cell adhesion molecule that is secreted or released after proteolysis, a mechanism that to our knowledge has not been described for immunoglobulin-like molecules. Genetic analyses indicate that nrm is an essential gene required for larval viability. We propose that Nrm may play a role as a cell adhesion molecule in clustering cells of the peripheral nervous system, neuronal fasciculation, and/or pathfinding.
Howard Hughes Medical Institute, Institute for Molecular Genetics, Baylor College of Medicine, Houston, Texas 77030.
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Kania
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Han
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Kim
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Bellen
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015815:Cell Adhesion Molecules / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D002449:Cell Aggregation; D002460:Cell Line; D016386:Chromosome Walking; D004252:DNA Mutational Analysis; D017931:DNA Primers; D004330:Drosophila / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins; D015870:Gene Expression; D015698:Genomic Library; D007136:Immunoglobulins / Q000737:chemistry / Q000235:genetics; D017403:In Situ Hybridization; D007814:Larva; D008969:Molecular Sequence Data; D009132:Muscles / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D009475:Neurons, Afferent / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D017433:Protein Structure, Secondary; D017386:Sequence Homology, Amino Acid; D014162:Transfection
D015815:Cell Adhesion Molecules; D017931:DNA Primers; D029721:Drosophila Proteins; D007136:Immunoglobulins; C083783:nrm protein, Drosophila