Bovine brain clathrin light chains impede heavy chain assembly in vitro.
Intact bovine brain clathrin triskelia, comprising three heavy and three light chains, require either 2 mM calcium or the assistance of protein co-factors for efficient assembly into regular cage structures (Keen, J. H., Willingham, M. C., and Pastan, I. (1979) Cell 16, 303-312). In contrast light chain-free heavy chains assemble readily in the absence of co-factors or calcium. Reconstitution of intact clathrin from heavy and light chains restores the calcium requirement. Our data indicate that light chains impede assembly by creating a kinetic trap rather than by perturbing the affinity of heavy chains for each other. This property suggests a function for light chains as regulatory subunits for clathrin assembly.
Ungewickell
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Max-Planck-Institut für Biochemie, Martinsried, Federal Republic of Germany.
Ungewickell
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D000818:Animals; D001923:Brain Chemistry; D002417:Cattle; D002850:Chromatography, Gel; D002966:Clathrin / Q000302:isolation & purification / Q000378:metabolism* / Q000648:ultrastructure; D004591:Electrophoresis, Polyacrylamide Gel; D008854:Microscopy, Electron
D002966:Clathrin