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Abstract
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Abstract
Objective Mammalian cells as the main host for
production of human proteins are incapable of complete c-carboxylation of over-expressed Vitamin K
Dependent (VKD) proteins. The Drosophila c-glutamyl carboxylase (DcC) has been shown to be more
efficient than its human counterpart in c-carboxylation
of human substrates, in vitro. Considering the
Drosophila c-carboxylase (DcC) efficiency, in comparison with its human counterpart, for recognition
and c-carboxylation of a human substrate in vitro, we
were determined to study the effect of the DcC on the
hFIX expression in a mammalian cell line. With this
aim, we examined co-expression of the DcC with the
hFIX, in a human cell line.
Results While the co-expression of a complete DcC
cDNA reduced the hFIX expression, a truncated form
of DcC could improve both the expression level (up to
1211 ng/106 cells/ml on the 4th day of post-transfection) and carboxylation of the expressed hFIX,
significantly (p \ 0.009).
Conclusions Our findings provided evidences for
potential of a partial fragment of the DcC for
improvement of the c-carboxylation of a human
substrate in a mammalian cell. Our experimental data,
in accordance with in silico analysis suggested that the
DcC C-terminal fragment, with the advantage of a
Kozak-like element has the potential of being
expressed as a separate internal translation unit, to
generate a peptide with appropriate c-carboxylase
activity.
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