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Arch Biochem Biophys. 1995 Mar 10;317(2):337-42.

In vitro reconstitution of phagosome-endosome fusion: evidence for regulation by heterotrimeric GTPases.

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Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110.


We have assessed the role of heterotrimeric GTPases on in vitro fusion of phagosomes and endosomes. Highly purified phagosomes were found to contain G alpha s, G alpha i1, G alpha i2, G alpha i3, and G beta subunits of heterotrimeric GTP-binding proteins. A functional role for G proteins was established using an in vitro phagosome-endosome fusion assay. First, addition of AlF4- and purified G beta gamma subunits to the in vitro assay blocked fusion, indicating that heterotrimeric G proteins may play a role, either direct or indirect, in phagosome maturation. Second, a striking inhibitory effect was observed when the vesicles were incubated with peptides that preferentially activate G alpha s. A similar effect on phagosome-endosome fusion was observed with cholera toxin, a reagent known to activate G alpha s. Our results suggest that one or more heterotrimeric G proteins, including Gs, mediate and/or regulate phagosome-endosome fusion.

[Indexed for MEDLINE]

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