| Autor: |
Hoffenberg, Simon, Liu, X., Nikolova, Lydia, Hall, Hassan S., Dai, Wenping, Baughn, Robert E., Dickey, Burton F., Barbieri, M. Alejandro, Aballay, Alejando, Stahl, Philip D., Knoll, Brian J. |
| Zdroj: |
Journal of Biological Chemistry; August 2000, Vol. 275 Issue: 32 p24661-24669, 9p |
| Abstrakt: |
The ras-related GTPase rab5 is rate-limiting for homotypic early endosome fusion. We used a yeast two-hybrid screen to identify a rab5 interacting protein, rab5ip. The cDNA sequence encodes a ubiquitous 75-kDa protein with an N-terminal transmembrane domain (TM), a central coiled-coil structure, and a C-terminal region homologous to several centrosome-associated proteins. rab5ip lacking the transmembrane domain (rab5ipTM(−)) had a greater affinity in vitrofor rab5-guanosine 5′-O-2-(thio)diphosphate than for rab5-guanosine 5′-3-O-(thio)triphosphate. In transfected HeLa cells, rab5ipTM(−) was partly cytosolic and localized (by immunofluorescence) with a rab5 mutant believed to be in a GDP conformation (GFP-rab5G78A) but not with GFP-rab5Q79L, a GTPase-deficient mutant. rab5ip with the transmembrane domain (rab5ipTM(+)) was completely associated with the particulate fraction and localized extensively with GFP-rab5wtin punctate endosome-like structures. Overexpression of rab5ipTM(+) using Sindbis virus stimulated the accumulation of fluid-phase horseradish peroxidase by BHK-21 cells, and homotypic endosome fusion in vitrowas inhibited by antibody against rab5ip. rab5ipTM(−) inhibited rab5wt-stimulated endosome fusion but did not inhibit fusion stimulated by rab5Q79L. rab5ip represents a novel rab5 interacting protein that may function on endocytic vesicles as a receptor for rab5-GDP and participate in the activation of rab5. |
| Databáze: |
Supplemental Index |
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