title: A T-lymphoma transmembrane glycoprotein (gp180) is linked to the cytoskeletal protein, fodrin.
abstract: A major mouse T-lymphoma surface glycoprotein (gp180) has been identified by labeling cells with 125I and [3H]glucosamine. After ligand-induced receptor patching and/or capping, the amount of gp 180 in the membrane-associated cytoskeleton fraction increases in direct proportion to the percentage of patched/capped cells. There is a parallel increase in the amount of fodrin in the membrane-associated cytoskeleton fraction. Evidence is presented that gp180 is the same as or very similar to the T-lymphocyte-specific glycoprotein T-200. An immunobinding assay of Nonidet P-40-solubilized plasma membrane selectively co-isolates gp180 and fodrin. After induction of receptor rearrangement, double-label immunofluorescence reveals that fodrin accumulated directly beneath gp180 patches and caps. Membrane extraction with Triton X-114 followed by sucrose gradient centrifugation permits isolation of a gp180-fodrin complex with a 1:1 molar ratio and sedimentation coefficient(s) of approximately 20. This complex remains stable during isoelectric focusing and exhibits a pl in the range of 5.2-5.7. On the basis of our results we conclude that gp180, an integral membrane glycoprotein, and fodrin, a component of the membrane-associated cytoskeleton, are closely associated into a complex. Furthermore, we contend that, through fodrin's association with actin, this complex is of functional significance in ligand-induced patching and capping of gp180. We also propose that, through lateral interactions in the plane of the membrane, the gp180-fodrin complex might be responsible for linking other surface receptors to the intracellular microfilament network during lymphocyte patching and capping.
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000032:analysis / Q000378:metabolism*; D002460:Cell Line; D003599:Cytoskeleton / Q000378:metabolism; D004347:Drug Interactions; D004591:Electrophoresis, Polyacrylamide Gel; D007152:Immunologic Capping; D007525:Isoelectric Focusing; D008223:Lymphoma / Q000378:metabolism*; D008565:Membrane Proteins / Q000032:analysis / Q000378:metabolism*; D051379:Mice; D008840:Microfilament Proteins / Q000032:analysis / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000032:analysis / Q000378:metabolism*; D011948:Receptors, Antigen, T-Cell / Q000032:analysis / Q000378:metabolism; D013601:T-Lymphocytes / Q000378:metabolism*; D013049:Spectrin
chemical_list: D002352:Carrier Proteins; D008565:Membrane Proteins; D008840:Microfilament Proteins; D009363:Neoplasm Proteins; D011948:Receptors, Antigen, T-Cell; D013049:Spectrin