Detergent solubility defines an alternative itinerary for a subpopulation of PDGF beta receptors.
Current models of platelet-derived growth factor (PDGF) beta receptor itinerary are based upon the properties of receptors recovered from nonionic detergent-solubilized cellular extracts. Comparing several commonly used cell extraction procedures, we have determined that up to 50% of immunoreactive PDGF beta receptors, reside in a Triton X-100 insoluble pool in a wide distribution of cultured cell lines, including Balb/c-3T3, NIH 3T3, and Swiss fibroblasts, primary murine and human fibroblasts, and primary human glial cells. Many properties of Triton insoluble receptors are distinct from the well-characterized PDGF beta receptors, including 1) delayed arrival of newly synthesized receptors into the Triton insoluble fraction, 2) prolonged half-life in the presence of PDGF, 3) increased abundance with increasing cell density, 4) inaccessibility to modification by extracellular compartment enzymes, 5) cofractionation with cytoskeletal proteins, and 6) a higher basal tyrosine phosphorylation state. PDGF stimulates accumulation of tyrosine phosphorylated PDGF beta receptors in the Triton X-100 insoluble fraction. Cell surface PDGF beta receptors modified by enzymatic desialylation redistribute to the insoluble fraction. These findings distinguish the itinerary of a large subpopulation of PDGF beta receptors from those characterized previously. Receptors in this fraction represent a long-lived tyrosine phosphorylated population that may effect responses for extended periods following ligand activation.
Coats
S R
SR
Department of Cell Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA.
Pledger
W J
WJ
Awazu
M
M
Daniel
T O
TO
D000818:Animals; D002452:Cell Count; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D003902:Detergents / Q000494:pharmacology*; D006801:Humans; D015151:Immunoblotting; D051379:Mice; D009439:Neuraminidase / Q000378:metabolism; D017830:Octoxynol / Q000494:pharmacology; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D010982:Platelet-Derived Growth Factor / Q000378:metabolism; D011233:Precipitin Tests; D020797:Receptor, Platelet-Derived Growth Factor beta; D017479:Receptors, Platelet-Derived Growth Factor / Q000378:metabolism*; D012995:Solubility; D013696:Temperature; D014357:Trypsin / Q000378:metabolism
D003902:Detergents; D010982:Platelet-Derived Growth Factor; D019000:Phosphotyrosine; D017830:Octoxynol; D003513:Cycloheximide; D020797:Receptor, Platelet-Derived Growth Factor beta; D017479:Receptors, Platelet-Derived Growth Factor; D009439:Neuraminidase; D014357:Trypsin