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Dimerization Properties of Rabaptin-5 and Its Isoforms

E. V. Korobko1,2, S. L. Kiselev1, and I. V. Korobko1*

1Institute of Gene Biology, Russian Academy of Sciences, ul. Vavilova 34/5, 119334 Moscow, Russia; fax: (495) 135-4105; E-mail: igorvk@igb.ac.ru

2University of Oslo, Centre for Medical Studies in Russia, ul. Vavilova 34/5, 119334 Moscow, Russia

* To whom correspondence should be addressed.

Received April 19, 2006; Revision received May 25, 2006
Rabaptin-5 plays an important role in intracellular membrane traffic acting as an effector molecule of small GTPases Rab5 and Rab4. It was previously demonstrated that Rabaptin-5 exists as a part of a large protein complex in vivo and is able to form dimers in vitro. Data of X-ray structural analysis suggest that dimerization of Rabaptin-5 is an important feature required for its interaction with Rab5 GTPase. Recently several isoforms of Rabaptin-5 characterized by various deletions in the polypeptide chains have been identified. These isoforms might exhibit functional properties that differ from those of Rabaptin-5. In this study, we have investigated dimerization properties of delta and gamma isoforms of Rabaptin-5. In addition, we have provided the first direct evidence for Rabaptin-5 dimerization in cells.
KEY WORDS: Rabaptin-5, Rabaptin-5 isoforms, dimerization, membrane transport

DOI: 10.1134/S0006297906120030