Unusual structural organization of the endocytic proteins AP180 and epsin 1.
Epsin and AP180/CALM are important endocytic accessory proteins that are believed to be involved in the formation of clathrin coats. Both proteins associate with phosphorylated membrane inositol lipids through their epsin N-terminal homology domains and with other components of the endocytic machinery through short peptide motifs in their carboxyl-terminal segments. Using hydrodynamic and spectroscopic methods, we demonstrate that the parts of epsin 1 and AP180 that are involved in protein-protein interactions behave as poorly structured flexible polypeptide chains with little or no conventional secondary structure. The predominant cytosolic forms of both proteins are monomers. Furthermore, we show that recombinant epsin 1, like AP180, drives in vitro assembly of clathrin cages. We conclude that the epsin N-terminal homology domain-containing proteins AP180/CALM and epsin 1 have a very similar molecular architecture that is designed for the rapid and efficient recruitment of the principal coat components clathrin and AP-2 at the sites of coated pit assembly.
Kalthoff
Christoph
C
Department of Cell Biology, Center of Anatomy, Hannover Medical School, D-30125 Hannover, Germany.
Alves
Jürgen
J
Urbanke
Claus
C
Knorr
Ruth
R
Ungewickell
Ernst J
EJ
D033942:Adaptor Proteins, Vesicular Transport; D000818:Animals; D001921:Brain / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry*; D002462:Cell Membrane / Q000378:metabolism; D002499:Centrifugation, Density Gradient; D002850:Chromatography, Gel; D002942:Circular Dichroism; D003600:Cytosol / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004705:Endocytosis; D006358:Hot Temperature; D007700:Kinetics; D008565:Membrane Proteins / Q000737:chemistry*; D008958:Models, Molecular; D034041:Monomeric Clathrin Assembly Proteins; D009479:Neuropeptides / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013395:Sucrose / Q000494:pharmacology; D013552:Swine; D033921:Vesicular Transport Proteins
D033942:Adaptor Proteins, Vesicular Transport; D002352:Carrier Proteins; D008565:Membrane Proteins; D034041:Monomeric Clathrin Assembly Proteins; D009479:Neuropeptides; C439003:PICALM protein, human; D010455:Peptides; D011994:Recombinant Proteins; D033921:Vesicular Transport Proteins; C439023:clathrin assembly protein AP180; C114154:epsin; D013395:Sucrose