Identification of proteins secreted from axons of embryonic dorsal-root-ganglia neurons.
Secretion of proteins from the growth cone has been implicated in axon growth and synapse formation and might be involved in the transmission of a variety of axon-derived regulatory signals during neurogenesis. In order to identify axonally secreted proteins, dorsal-root-ganglia neurons from chicken embryos were cultured in a compartmentalized cell culture system that allows separate access to neuronal cell somas and axons. The proteins synthesized by the neurons were metabolically labeled by addition of [35S]methionine to the compartment containing the cell somas; the proteins released from the axons were harvested from the culture medium of the axonal compartment. Two-dimensional gel electrophoresis revealed two axonally secreted proteins with apparent molecular mass of 132-140 kDa and 54-60 kDa; they were termed axonin-1 and axonin-2, respectively. Both axonins were found to be secreted from a variety of neuronal cell cultures, but not from any of the nonneuronal cultures investigated, and hence might be neuron-specific. Virtual absence of these proteins from the axonal protein pattern suggests constitutive secretion. The information acquired on coordinates and spot morphology of these proteins in two-dimensional gel electrophoresis provides a useful assay for their purification.
Stoeckli
E T
ET
Institute of Biochemistry, University of Zürich.
Lemkin
P F
PF
Kuhn
T B
TB
Ruegg
M A
MA
Heller
M
M
Sonderegger
P
P
D000818:Animals; D001219:Aspartate Aminotransferases / Q000378:metabolism; D001369:Axons / Q000378:metabolism*; D002478:Cells, Cultured; D002642:Chick Embryo; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D005727:Ganglia, Spinal / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D008970:Molecular Weight; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000378:metabolism*; D009474:Neurons / Q000166:cytology; D013569:Synapses / Q000502:physiology
D009419:Nerve Tissue Proteins; D001219:Aspartate Aminotransferases