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ID 25974
file
creator
Satake, Makoto
Kamino, Kei
Michibata, Hitoshi
subject
vanadium
ascidian
metal binding protein
gene expression
NDC
Biology
abstract
The blood cells of ascidians accumulate extremely high levels of the transition metal vanadium. We previously isolated four vanadium-binding proteins (Vanabins 1–4) and a homologous protein (VanabinP) from the vanadium-rich ascidian Ascidia sydneiensis samea. In the present study, we identified cDNAs encoding five different Vanabin2-related proteins in A. sydneiensis samea blood cells. It was notable that the sequences of the encoded proteins vary from that of Vanabin2 at up to 14 specific positions, while both the polypeptide length and the 18 cysteine residues were completely conserved. The most divergent protein, named 14MT, differed from Vanabin2 at all 14 positions. Using immobilized metal-ion affinity chromatography, we found that Vanabin2 and 14MT have the same metal ion selectivity, but the overall affinity of 14MT for VO2+ is higher than that of Vanabin2. Binding number for VO2+ ions was same between Vanabin2 and 14MT as assessed by gel filtration. These results suggested that sequence variations were under strict evolutionary constraints and high affinity binding sites for VO2+ are conserved among Vanabin2 variants.
journal title
Biochimica et Biophysica Acta (BBA) - General Subjects
volume
Volume 1780
issue
Issue 7-8
start page
1010
end page
1015
date of issued
2008-07
publisher
Elsevier Science BV
issn
0304-4165
ncid
publisher doi
language
eng
nii type
Journal Article
HU type
Journal Articles
DCMI type
text
format
application/pdf
text version
author
rights
Copyright (c) 2008 Elsevier B.V.
relation url
department
Graduate School of Science