title: Two classes of binding sites for uncoating protein in clathrin triskelions.
abstract: Clathrin released from coated vesicles or empty cages by the ATP-dependent action of uncoating protein exists as a complex with the uncoating protein. Despite its apparent consumption during a round of uncoating, we have found that uncoating protein functions as an enzyme in that it rapidly and spontaneously recycles from its product (triskelions) to its substrate (cages). The binding of uncoating protein to clathrin triskelions is a complex equilibrium that involves the interaction of uncoating protein with at least two distinct sites on the clathrin molecule. Limited proteolysis dissected clathrin into two domains, each of which contained distinct binding sites. Binding to one of these sites, located on the proximal leg of a triskelion, was dependent upon the presence of light chains and was unstable to gel filtration. Binding to the second kind of site, located on the distal portion of a triskelion leg, was stable to gel filtration and was independent of the presence of light chains.
authors.forename: S L
authors.initials: SL
authors.lastname: Schmid
authors.forename: J E
authors.initials: JE
authors.lastname: Rothman
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D001921:Brain / Q000201:enzymology* / Q000648:ultrastructure; D002352:Carrier Proteins / Q000302:isolation & purification / Q000378:metabolism*; D002417:Cattle; D002966:Clathrin / Q000378:metabolism*; D003034:Coated Pits, Cell-Membrane / Q000201:enzymology / Q000648:ultrastructure*; D011992:Endosomes / Q000648:ultrastructure*; D050883:HSC70 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D007700:Kinetics; D008970:Molecular Weight; D010446:Peptide Fragments / Q000032:analysis; D011485:Protein Binding; D014357:Trypsin
chemical_list: D002352:Carrier Proteins; D002966:Clathrin; D050883:HSC70 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D010446:Peptide Fragments; D000255:Adenosine Triphosphate; D014357:Trypsin; D000251:Adenosine Triphosphatases