title: Characterization of coated-vesicle adaptors: their reassembly with clathrin and with recycling receptors.
abstract: Adaptors sort out those receptors that participate in assembly of coated pits from those that are excluded. Two distinct adaptor units have so far been identified: (1) adaptors restricted to plasma membrane coated pits (HA-II type, named according to their elution position during hydroxylapatite chromatography) and (2) adaptors restricted to Golgi region coated pits (HA-I type). Adaptors contain a heterodimer of two 100-kDa polypeptides, a beta-adaptin (possibly carrying an essentially common clathrin-binding domain) and a distinct alpha- or gamma-adaptin characteristic of the type of adaptor and its specific location. Each adaptor in constructed from four different polypeptides. Thus HA-II adaptors contain a beta-adaptin and an alpha-adaptin in combination with a 50-kDa protein and a 16-kDa polypeptide. The HA-I adaptors contain a beta-adaptin and a gamma-adaptin in combination with a 47-kDa protein and a 19-kDa polypeptide. Both types of adaptors and also a 180-kDa polypeptide will promote the assembly of clathrin to form coats, the size range of which appears to be relatively restricted compared to cages made from clathrin alone. The HA-II adaptors, characteristic of plasma membrane coated pits, bind to the cytoplasmic tail of the LDL receptor. They also assemble with the mannose 6-phosphate receptor in vitro in the absence of membrane. When clathrin is included, the adaptors promote the assembly of coats containing bound receptor.
authors.affiliation: MRC Laboratory of Molecular Biology, Cambridge, England.
authors.forename: B M
authors.initials: BM
authors.lastname: Pearse
mesh_terms: D000818:Animals; D001921:Brain / Q000648:ultrastructure; D002021:Buffers; D002417:Cattle; D002458:Cell Fractionation / Q000379:methods; D002499:Centrifugation, Density Gradient / Q000379:methods; D002966:Clathrin / Q000302:isolation & purification / Q000502:physiology*; D003034:Coated Pits, Cell-Membrane / Q000502:physiology / Q000648:ultrastructure*; D004591:Electrophoresis, Polyacrylamide Gel; D011992:Endosomes / Q000648:ultrastructure*; D007202:Indicators and Reagents; D008297:Male; D008961:Models, Structural; D008970:Molecular Weight; D011956:Receptors, Cell Surface / Q000502:physiology*; D014461:Ultracentrifugation / Q000379:methods
chemical_list: D002021:Buffers; D002966:Clathrin; D007202:Indicators and Reagents; D011956:Receptors, Cell Surface