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ID 15044
file
creator
Yoshinaga, Masafumi
Yamaguchi, Nobuo
Kamino, Kei
Michibata, Hitoshi
subject
Ascidian
Digestive system
Glutathione transferase
Metal accumulation
Vanadium
NDC
Biology
abstract
Some ascidians accumulate vanadium in vanadocytes, which are vanadium-containing blood cells, at high levels and with high selectivity. However, the mechanism and physiological significance of vanadium accumulation remain unknown. In this study, we isolated novel proteins with a striking homology to glutathione transferases (GSTs), designated AsGST-I and AsGST-II, from the digestive system of the vanadium-accumulating ascidian Ascidia sydneiensis samea, in which the digestive system is thought to be involved in vanadium uptake. Analysis of recombinant AsGST-I confirmed that AsGST-I has GST activity and forms a dimer, as do other GSTs. In addition, AsGST-I was revealed to have vanadium-binding activity, which has never been reported for GSTs isolated from other organisms. AsGST-I bound about 16 vanadium atoms as either V(IV) or V(V) per dimer, and the apparent dissociation constants for V(IV) and V(V) were 1.8 × 10-4 M and 1.2 × 10-4 M, respectively. Western blot analysis revealed that AsGSTs were expressed in the digestive system at exceptionally high levels, although they were localized in almost all organs and tissues examined. Considering these results, we postulate that AsGSTs play important roles in vanadium accumulation in the ascidian digestive system.
journal title
Biochimica et Biophysica Acta - General Subjects
volume
Volume 1760
issue
Issue 3
start page
495
end page
503
date of issued
2006-03
publisher
Elsevier B.V.
issn
0304-4165
ncid
publisher doi
pubmed id
language
eng
nii type
Journal Article
HU type
Journal Articles
DCMI type
text
format
application/pdf
text version
author
rights
Copyright (c) 2006 Elsevier B.V.
relation is version of URL
http://dx.doi.org/10.1016/j.bbagen.2006.01.008
department
Graduate School of Science