Differential expression pattern of Rab-GDI isoforms during the parotid gland secretion cycle

Moran Benhar, Hassia Boschwitz, Michal Linial*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Rab GDP dissociation inhibitor (GDI) plays an important role in regulating the GDP/GTP cycle of small GTP binding proteins of the Rab family. It also regulates their association to membranes. The small family of Rab- GDI consists of several closely related isoforms, the functional differences between which are still unknown. Here we show that multiple GDI isoforms are expressed in rat parotid gland and that the individual GDI isoforms have a characteristic expression both at the RNA and at the protein level, during the parotid secretory cycle. GDIα, the major isoform in brain, is expressed throughout the secretory process and is equally distributed between cytoplasmic and membranous fractions. In contrast, an isoform related to, but different from GDIβ is found predominantly in the cytoplasmic fraction and its expression is detected only after β-adrenergic stimulation of the gland, at the end of the secretion phase, when exocytosis is already completed. The induction of such a GDI isoform at the beginning of the recovery stage correlates with the expression pattern of Rab1 and Rab5, but not Rab2 and Rab4. Our results suggest different functional roles for multiple GDI isoforms along the secretion and recovery phases in rat parotid gland.

Original languageAmerican English
Pages (from-to)207-215
Number of pages9
JournalExperimental Cell Research
Volume233
Issue number1
DOIs
StatePublished - 25 May 1997

Bibliographical note

Funding Information:
We thank Z. Elazar and D. Parnas for critical reading of the manuscript and suggestions. We thank Alomone Lab (Israel) for large-scale af®nity puri®cation of GDI antibodies. This work was partially supported by the Ministry for Science, by the German±Israeli Foundation, and by the Israel Cancer Research Foundation.

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