Attenuated glutamine synthetase as a selection marker
View Patent ↗Disclosed is an expression vector comprising a polynucleotide encoding for a glutamine synthetase with reduced activity compared to a wild type glutamine synthetase. Also disclosed are host cells, methods for preparing stable cell line, methods of producing polypeptide of interest, and kits thereof.
1. An expression vector comprising a polynucleotide encoding an attenuated glutamine synthetase comprising a single amino acid substitution with alanine at position 305 of a wild type glutamine synthetase comprising the amino acid sequence set forth in SEQ ID NO: 2.
2. The expression vector of claim 1 , wherein the polynucleotide encoding the attenuated glutamine synthetase is operatively linked to a promoter.
3. The expression vector of claim 1 , wherein the polynucleotide encoding the attenuated glutamine synthetase is not linked to a promoter.
4. A kit comprising the expression vector of claim 1 .
5. The kit of claim 4 , wherein the kit further comprises at least one of the following:
(i) a host cell having no glutamine synthetase activity; and
( 11 ) a transfection medium or means to carry out a transfection;
and/or wherein the kit further comprises a glutamine free cell culture medium.