Microenvironment and effect of energy depletion in the nucleus analyzed by mobility of multiple oligomeric EGFPs

¹ Laboratory of Supramolecular Biophysics, R.I.E.S, Hokkaido University
² Nanosystems Physiolog , R.I.E.S, Hokkaido University

^* To whom correspondence should be addressed. E-mail: kinjo{at}imd.es.hokudai.ac.jp.

Submitted on December 9, 2005
Revised on January 17, 2006
Accepted on 11 August 2006

	Abstract

Four different tandem EGFPs were constructed to elucidate the nuclear microenvironment by quantifying its diffusional properties in both aqueous solution and the nuclei of living cells. Diffusion of tandem EGFP was dependent on the length of the protein as a rod-like molecule or molecular ruler in solution. On the other hand, we found two kinds of mobility, fast diffusional mobility and much slower diffusional mobility depending on cellular compartments in living cells. Diffusion in the cytoplasm and the nucleoplasm was mainly measured as fast diffusional mobility. In contrast, diffusion in the nucleolus was complex and mainly much slower diffusional mobility, although both the fast and the slow diffusional mobilities were dependent on the protein length. Interestingly, we found that diffusion in the nucleolus was clearly changed by energy depletion, even though the diffusion in the cytoplasm and the nucleoplasm was not changed. Our results suggest that the nucleolar microenvironment is sensitive to energy depletion and very different from the nucleoplasm.

Key Words: ATP, fluorescence correlation spectroscopy, molecular ruler, nuclear, nucleolar, tandem EGFP

This article has been cited by other articles:

				Y. Noda, S. Horikawa, E. Kanda, M. Yamashita, H. Meng, K. Eto, Y. Li, M. Kuwahara, K. Hirai, C. Pack, et al. Reciprocal interaction with G-actin and tropomyosin is essential for aquaporin-2 trafficking J. Cell Biol., August 11, 2008; 182(3): 587 - 601. [Abstract] [Full Text] [PDF]