title: Selective externalization of an ATP-binding protein structurally related to the clathrin-uncoating ATPase/heat shock protein in vesicles containing terminal transferrin receptors during reticulocyte maturation.
abstract: Transferrin receptors are lost from reticulocytes in vesicles that are released during the final stage of erythrocyte maturation (Pan, B. T., and Johnstone, R. M. (1983) Cell 33, 967-977). Transferrin receptor-containing vesicles have a major protein component present in a 1:1 ratio with the receptor that migrates on sodium dodecyl sulfate gels as two polypeptides of Mr = 71,000 and 72,000. The Mr = 71,000/72,000 doublet is indistinguishable from the clathrin-uncoating ATPase/heat shock protein based on cross-reaction with affinity-purified antibody against the uncoating protein, by comparison of peptide maps of the Mr = 72,000 and 71,000 polypeptides and the uncoating protein, and by selective binding of these polypeptides to ATP-agarose. This finding suggests a possible activity of proteins related to the uncoating/heat shock protein family in the disposal of aged membrane proteins by a pathway independent of lysosomes.
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000097:blood*; D004591:Electrophoresis, Polyacrylamide Gel; D004910:Erythrocyte Membrane / Q000378:metabolism*; D050883:HSC70 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000097:blood*; D006801:Humans; D007163:Immunosorbent Techniques; D008970:Molecular Weight; D011990:Receptors, Transferrin / Q000378:metabolism*; D012156:Reticulocytes / Q000378:metabolism*; D012756:Sheep
chemical_list: D002352:Carrier Proteins; D050883:HSC70 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; C494371:HSPA8 protein, human; D006360:Heat-Shock Proteins; D011990:Receptors, Transferrin