Targeting signals and subunit interactions in coated vesicle adaptor complexes.

There are two clathrin-coated vesicle adaptor complexes in the cell, one associated with the plasma membrane and one associated with the TGN. The subunit composition of the plasma membrane adaptor complex is alpha-adaptin, beta-adaptin, AP50, and AP17; while that of the TGN adaptor complex is gamma-adaptin, beta'-adaptin, AP47, and AP19. ...
To search for adaptor targeting signals, we have constructed chimeras between alpha-adaptin and gamma-adaptin within their NH2-terminal domains. We have identified stretches of sequence in the two proteins between amino acids approximately 130 and 330-350 that are essential for targeting. Immunoprecipitation reveals that this region determines whether a construct coassemblies with AP50 and AP17, or with AP47 and AP19. These observations suggest that these other subunits may play an important role in targeting. In contrast, beta- and beta'-adaptins are clearly not involved in this event. Chimeras between the alpha- and gamma-adaptin COOH-terminal domains reveal the presence of a second targeting signal. We have further investigated the interactions between the adaptor subunits using the yeast two-hybrid system. Interactions can be detected between the beta/beta'-adaptins and the alpha/gamma-adaptins, between the beta/beta'-adaptins and the AP50/AP47 subunits, between alpha-adaptin and AP17, and between gamma-adaptin and AP19. These results indicate that the adaptor subunits act in concert to target the complex to the appropriate membrane.
Mesh Terms:
Adaptor Protein Complex 1, Adaptor Protein Complex 2, Adaptor Protein Complex alpha Subunits, Adaptor Protein Complex beta Subunits, Adaptor Protein Complex gamma Subunits, Adaptor Protein Complex mu Subunits, Adaptor Protein Complex sigma Subunits, Adaptor Proteins, Vesicular Transport, Animals, Cell Membrane, Coated Vesicles, Fibroblasts, Fluorescent Antibody Technique, Golgi Apparatus, Membrane Proteins, Rats, Recombinant Fusion Proteins
J. Cell Biol.
Date: Nov. 01, 1995
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