Cooperation of GGAs and AP-1 in packaging MPRs at the trans-Golgi network.

The Golgi-localized, gamma-ear-containing, adenosine diphosphate ribosylation factor-binding proteins (GGAs) are multidomain proteins that bind mannose 6-phosphate receptors (MPRs) in the Golgi and have an essential role in lysosomal enzyme sorting. Here the GGAs and the coat protein adaptor protein-1 (AP-1) were shown to colocalize in clathrin-coated buds of the trans-Golgi ...
networks of mouse L cells and human HeLa cells. Binding studies revealed a direct interaction between the hinge domains of the GGAs and the gamma-ear domain of AP-1. Further, AP-1 contained bound casein kinase-2 that phosphorylated GGA1 and GGA3, thereby causing autoinhibition. This could induce the directed transfer of the MPRs from GGAs to AP-1. MPRs that are defective in binding to GGAs are poorly incorporated into AP-1-containing clathrin-coated vesicles. Thus, the GGAs and AP-1 interact to package MPRs into AP-1-containing coated vesicles.
Mesh Terms:
ADP-Ribosylation Factors, Adaptor Proteins, Vesicular Transport, Animals, Biological Transport, Carrier Proteins, Cattle, Cell Line, Clathrin-Coated Vesicles, Hela Cells, Humans, L Cells (Cell Line), Membrane Proteins, Mice, Mutation, Phosphorylation, Protein Binding, Receptor, IGF Type 2, Recombinant Proteins, trans-Golgi Network
Science
Date: Sep. 06, 2002
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