Sub-cellular localization of suppressor of potassium transport defect 3 (SKD3) into nucleus and nuclear matrix

S Thanumalayan

doi:10.17485/ijst/2008/v1i3/4

Abstract

Suppressor of Potassium Transport Defect 3 (SKD3) is a mammalian homologue of Escherichia coli ClpB and S. cerevisiae Hsp104. While the exact cellular functions of SKD3 are not known, the functions of its microbial and yeast homologues have been well documented. The study presents new evidence on the localization of the protein under stress conditions like heat shock and H 2 O 2 treatment. Immunofluorescence study of heat stressed cells showed that the protein was redistributed to large foci in the nucleus while cytoplasmic staining remained unaltered. Upon H 2 O 2 treatment, the SKD3 protein level is increased both in the cytoplasm and nucleus. The outcome of this study reveals the fact that SKD3 may be a component of nucleus as well as nuclear scaffold which has a direct regulatory role during stress.

Highlights

Cellular homeostasis is one of the important features of living organism
ClpB is a member of Caseinolytic protease (Clp) family protein first identified in Escherichia coli (Gottesman et al, 1990), known for its remarkable capacity to rescue the aggregated proteins by its chaperone activity (Barnett et al, 2005; Doyle et al, 2007)
It has four ankyrin repeats that are essential for proteinprotein interactions and two nucleotide binding sites (ATP binding site) at the C-terminal end suggesting that SKD3 may be involved ATP dependent proteolytic activity of misfolded and aggregated proteins

Summary

Introduction

Cellular homeostasis is one of the important features of living organism. Whenever this steady state is disrupted by physiological changes such as heat shock and ionizing radiation etc., the repair/removal of damaged proteins becomes necessary for cell survival. Earlier reports in Drosophila tissues and some of the mammalian cells have shown Hsp proteins present in both cytoplasm and nucleus under normal conditions. Focus has been made on the sub cellular localization of SKD3 in normal and stressed conditions in mammalian cells since its homologue proteins ClpB and Hsp[104] have been shown to play important roles in bacteria and yeasts in response to various stresses.

Results

Conclusion