The Markey Scholars Conference Proceedings (2004) / Chapter Skim
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10 AAK1, A Novel Kinase That Regulates Cargo Selection for Clatherin-Mediated Endocytosis
10 AAK1, A Novel Kinase That Regulates Cargo Selection for Clatherin-Mediated Endocytosis
Pages 90-96
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From page 90... ...
The coat proteins assemble into a polygonal lattice, which forms curved structures that help to deform and invaginate the membrane forming coated pits. Finally, membrane fission, which is regulated by the GTPase dynamin that assembles into a collar-like structure encircling the neck of deeply invaginated coated pits, releases a transport vesicle that carries concentrated cargo receptor and ligand complexes into the cell.
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From page 91... ...
Finally, we can focus on measuring the earliest events in vesicle formation, by supplementing assays performed in the presence of limiting concentrations of cytosol with purified coat proteins. The coat protein-stimulated sequestration of BSSTfn into constricted coated pits reflects de novo coat assembly.
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From page 92... ...
also bind a number of accessory molecules whose exact function in endocytosis has yet to be established. The mu subunit recognizes specific sorting motifs on cargo molecules, and in particular has been shown to recognize tyrosine-based sorting motifs such as those found in the transferrin receptor.
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From page 93... ...
What are the consequences of this phosphorylation of mu? As I mentioned, the mu subunit recognizes cargo-sorting motifs on cargo molecules.
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From page 94... ...
First, however, we wanted to see whether there were any other substrates that we could detect in these more complex cell extracts. When AAK1 is incubated with either cell membranes or cytosol, the principal product, other than autophosphorylation of AAK1, is the mu subunit.
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From page 95... ...
Our current working model to explain all of the observations we have, not all of which I have described to you, is that the effective concentration of cargo molecules into coated pits requires cycles of phosphorylation and dephosphorylation of the mu subunit, mediated by AAK1. The recently published three-dimensional structure of the AP2 core (Collins, B.M., et al.
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From page 96... ...
Our future efforts will be directed towards testing this model and elucidating the role of AAK1 in regulating clathrin-mediated endocytosis. NOTE: The following papers report some of the studies described here, Conner, S
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