Regulation of the GTPase cycle of the neuronally expressed Ras-like GTP- binding protein Rab3A

E. S. Burstein, W. H. Brondyk, I. G. Macara, K. Kaibuchi, Y. Takai

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23 Citations (Scopus)


The small GTP-binding protein Rab3A (identical to smg p25A) is expressed in neural/exocrine/endocrine cells, is distributed between the cytosol and secretory vesicle membranes, and may cycle between these locations to regulate exocytosis. It is proposed that the GTP/GDP state of Rab3A controls this distribution. In PC12 cells, cytosolic Rab3A is predominantly GDP- bound, whereas membrane-associated Rab3A is approximately 50% GTP-bound. Two cytosolic factors, GDP dissociation inhibitor (GDI) and guanine nucleotide releasing factor (GRF), act only on GDP · Rab3A, and preferentially with post-translationally modified Rab3A. Rab3A GTPase-activating protein (GAP) does not preferentially act on processed Rab3A, and interacts selectively with GTP · Rab3A. GDI antagonizes GRF but not GAP activity toward Rab3A. These data are consistent with the concept of an ordered Rab3A cycle controlled by factors that regulate the guanine-nucleotide binding state of Rab3A.

Original languageEnglish
Pages (from-to)22247-22250
Number of pages4
JournalJournal of Biological Chemistry
Issue number30
Publication statusPublished - 1993
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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