A novel Rab9 effector required for endosome-to-TGN transport

Elva D Diaz, Frauke Schimmöller, Suzanne R. Pfeffer

Research output: Contribution to journalArticle

107 Citations (Scopus)

Abstract

Rab9 GTPase is required for the transport of mannose 6-phosphate receptors from endosomes to the trans-Golgi network in living cells, and in an in vitro system that reconstitutes this process. We have used the yeast two-hybrid system to identify proteins that interact preferentially with the active form of Rab9. We report here the discovery of a 40-kD protein (p40) that binds Rab9-GTP with roughly fourfold preference to Rab9-GDP. p40 does not interact with Rab7 or K-Ras; it also fails to bind Rab9 when it is bound to GDI. The protein is found in cytosol, yet a significant fraction (~30%) is associated with cellular membranes. Upon sucrose density gradient flotation, membrane-associated p40 cofractionates with endosomes containing mannose 6-phosphate receptors and the Rab9 GTPase. p40 is a very potent transport factor in that the pure, recombinant protein can stimulate, significantly, an in vitro transport assay that measures transport of mannose 6-phosphate receptors from endosomes to the trans-Golgi network. The functional importance of p40 is confirmed by the finding that anti-p40 antibodies inhibit in vitro transport. Finally, p40 shows synergy with Rab9 in terms of its ability to stimulate mannose 6-phosphate receptor transport. These data are consistent with a model in which p40 and Rab9 act together to drive the process of transport vesicle docking.

Original languageEnglish (US)
Pages (from-to)283-290
Number of pages8
JournalJournal of Cell Biology
Volume138
Issue number2
DOIs
StatePublished - Jul 28 1997
Externally publishedYes

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Endosomes
IGF Type 2 Receptor
trans-Golgi Network
GTP Phosphohydrolases
Guanine Nucleotide Dissociation Inhibitors
Transport Vesicles
Two-Hybrid System Techniques
Proteins
Membranes
adjuvant P40
Guanosine Triphosphate
Recombinant Proteins
Cytosol
Sucrose
Anti-Idiotypic Antibodies

ASJC Scopus subject areas

  • Cell Biology

Cite this

A novel Rab9 effector required for endosome-to-TGN transport. / Diaz, Elva D; Schimmöller, Frauke; Pfeffer, Suzanne R.

In: Journal of Cell Biology, Vol. 138, No. 2, 28.07.1997, p. 283-290.

Research output: Contribution to journalArticle

Diaz, Elva D ; Schimmöller, Frauke ; Pfeffer, Suzanne R. / A novel Rab9 effector required for endosome-to-TGN transport. In: Journal of Cell Biology. 1997 ; Vol. 138, No. 2. pp. 283-290.
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