Thy-1 and AvGp50 signal transduction complex in the avian nervous system: c-Fyn and G alpha i protein association and activation of signalling pathways.
We have previously reported the isolation of two distinct populations of detergent resistant membrane complexes (DRMC's) from day-old chick brain (Henke et al.: J Neurosci Res 45:617-630, 1996). We now show that the glycosylphosphatidylinositol-anchored proteins Thy-1 and AvGp50 are associated in a signalling complex with c-Fyn, the heterotrimeric G alpha i subfamily members G alpha i-3, G alpha z, and G alpha o, alpha and beta tubulin, and a number of other phosphoproteins in immunocomplexes isolated from both populations of DRMC's. Activation of this signalling complex via Thy-1 monoclonal antibody incubation with chick forebrain cells, elicited a decrease in total phosphoprotein profile and tyrosine kinase activity present in DRMC fractions isolated from these cells, while AvGp50 and control antibodies had no effect. Down-regulation of the DRMC phosphoprotein profile was accompanied by an increase in the Thy-1-associated signalling complex, suggesting that activation of this complex initiates the decreases seen in overall DRMC kinase activity. This signalling complex provides the basis for GPI-anchored protein-mediated signal transduction within the unique plasma membrane domains represented by DRMC's.
Henke
R C
RC
Development Neurobiology Unit, Children's Medical Research Institute, Wentworthville, NSW, Australia.
Seeto
G S
GS
Jeffrey
P L
PL
D000818:Animals; D000911:Antibodies, Monoclonal; D015816:Cell Adhesion Molecules, Neuronal / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D002642:Chick Embryo; D002784:Cholesterol / Q000378:metabolism; D003902:Detergents; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000032:analysis / Q000378:metabolism; D017261:Glycosylphosphatidylinositols / Q000378:metabolism; D039841:Leukocyte L1 Antigen Complex; D008562:Membrane Glycoproteins / Q000378:metabolism; D008563:Membrane Lipids / Q000378:metabolism; D039842:Neural Cell Adhesion Molecule L1; D019006:Neural Cell Adhesion Molecules / Q000276:immunology / Q000378:metabolism*; D016501:Neurites / Q000737:chemistry / Q000201:enzymology; D010750:Phosphoproteins / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000032:analysis / Q000378:metabolism; D016548:Prosencephalon / Q000737:chemistry / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051076:Proto-Oncogene Proteins c-fyn; D015398:Signal Transduction / Q000502:physiology*; D013347:Subcellular Fractions / Q000737:chemistry / Q000201:enzymology; D018800:Thy-1 Antigens / Q000276:immunology / Q000378:metabolism*; D014404:Tubulin / Q000032:analysis / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism
D000911:Antibodies, Monoclonal; D015816:Cell Adhesion Molecules, Neuronal; D003902:Detergents; D017261:Glycosylphosphatidylinositols; D039841:Leukocyte L1 Antigen Complex; D008562:Membrane Glycoproteins; D008563:Membrane Lipids; D039842:Neural Cell Adhesion Molecule L1; D019006:Neural Cell Adhesion Molecules; D010750:Phosphoproteins; D011518:Proto-Oncogene Proteins; D018800:Thy-1 Antigens; D014404:Tubulin; C106492:avian glycoprotein 50-kDa; D019000:Phosphotyrosine; D014443:Tyrosine; D002784:Cholesterol; D011505:Protein-Tyrosine Kinases; D051076:Proto-Oncogene Proteins c-fyn; D010744:Phosphoric Monoester Hydrolases; D019206:GTP-Binding Protein alpha Subunits, Gi-Go