Clathrin and adaptors.
Clathrin and adaptors are components of clathrin-coated pits and vesicles. The AP-1 adaptor complex is associated with clathrin-coated vesicles budding from the TGN, while the AP-2 adaptor complex is associated with clathrin-coated vesicles budding from the plasma membrane. The clathrin forms a polyhedral lattice and is believed to be the driving force behind membrane invagination leading to vesicle budding. The adaptors attach the clathrin to the membrane and also interact with the cytoplasmic domains of selected transmembrane proteins, causing these proteins to become concentrated in clathrin-coated vesicles. Clathrin-coated vesicles budding from the TGN have been implicated in the sorting of newly synthesised lysosomal enzymes, while clathrin-coated vesicles budding from the plasma membrane facilitate the receptor-mediated endocytosis of ligands, such as low density lipoproteins and transferrin. A novel adaptor-related complex, AP-3, has recently been identified, which is recruited onto membranes of the TGN and a more peripheral compartment but does not appear to be associated with clathrin. Genetic studies indicate that AP-3 plays a role in the sorting of proteins to lysosomes and lysosome-related organelles.
Hirst
J
J
Department of Clinical Biochemistry, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge CB2 2QR, UK. jh228@cam.ac.uk
Robinson
M S
MS
D033963:Adaptor Protein Complex 3; D033965:Adaptor Protein Complex alpha Subunits; D033981:Adaptor Protein Complex delta Subunits; D033942:Adaptor Proteins, Vesicular Transport; D000818:Animals; D002966:Clathrin / Q000235:genetics / Q000502:physiology*; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D034041:Monomeric Clathrin Assembly Proteins; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*
C491904:AP3D1 protein, human; D033963:Adaptor Protein Complex 3; D033965:Adaptor Protein Complex alpha Subunits; D033981:Adaptor Protein Complex delta Subunits; D033942:Adaptor Proteins, Vesicular Transport; D002966:Clathrin; D008565:Membrane Proteins; D034041:Monomeric Clathrin Assembly Proteins; D014157:Transcription Factors; C439023:clathrin assembly protein AP180