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Human IgG2 - Lucia tag
Heavy chain constant region expression plasmid - Human IgG2 - Lucia tag
pFUSE-Lucia-CHIg-hG2 is a cloning plasmid that expresses the constant region of the human IgG2 heavy chain. It contains a multiple cloning site upstream of the constant region to enable cloning of the heavy chain variable region.
This plasmid is designed for antibody generation when co-transfected into mammalian cells with the light chain variable region cloned into pFUSE-CLIg.
pFUSE-Lucia-CHIg-hG2 contain the secreted luciferase (Lucia) gene upstream of the MCS and the CH region to serve as a tag to facilitate the detection and quantification of recombinant antibodies.Back to the top
- Constant region of the human IgG2 heavy chain
- Lucia secreted luciferase tag
Lucia luciferase is a secreted protein, therefore, the VH sequence should not include a signal sequence.
Plasmids is selectable with Zeocin™ in E.coli and mammalian cells.
These products are covered by a Limited Use License (See Terms and Conditions).Back to the top
- 20 µg of lyophilized DNA
- 1 ml of Zeocin® (100 mg/ml)
Product is shipped at room temperatureBack to the top
Antibody generation using pFUSE-Lucia-CHIg & pFUSE-CLIg
1- Obtaining VH and VL sequences
To obtain the cDNA sequence of the VH and VL regions from an antibody producing hybridoma, total RNA or mRNA is extracted and reverse transcribed to cDNA. PCR is performed with 5’ degenerate primers to anneal to the unknown VH and VL regions and the 3’ primers designed to anneal to the ‘known’ CH and CL regions. Alternatively 5’ RACE can be used. The resulting amplicons are sequenced.
2- Cloning into pFUSE-CHIg and pFUSE2-CLIg
Once the VH and VL sequence are known, inserts for cloning into the plasmids can be generated.In pFUSE-Lucia-CHIg-hG2, the constant region of the human IgG2 heavy chain is preceded by a multiple cloning site containing four restriction sites: Acc 651, Eco RI, Xho I and Nhe I. The first three restriction sites can be used for insertion of the 5’end of the variable region, taking care to clone in frame with the Lucia luciferase sequence. In pFUSE-Lucia-CHIg-hG2, Nhe I must be used for insertion of the 3’end of the variable region. Nhe I must be reconstituted to maintain the integrity of the constant region. Therefore we recommend to introduce by PCR an Nhe I site at the 3’ end of the variable region in frame with the constant region.
3- Antibody production
Cotransfect mammalian cells, such as 293 and CHO cells, with the recombinant plasmids pFUSE2-CLIg encoding the light chain and pFUSE-CHIg encoding the heavy chain. Antibody production depends greatly on the ratio of heavy chain and light chain expression. Typically, pFUSE-CHIg to pFUSE2-CLIg ratio of 2:3 is used to cotransfect mammalian cells. Use blasticidin and Zeocin™ to select pFUSE2-CLIg and pFUSE-CHIg respectively.
Antibody production can be analyzed by different techniques including SDS-PAGE, flow cytometry, ELISA, or a bioactivity assay: the luciferase levels in the supernatant could be determined using QUANTI-Luc™.
4- Antibody purificationBack to the top
1- Schematic representation of a Lucia luciferase-tagged antibody
2- Luciferase activity of Lucia-tagged anti-hTNF-α antibodies.
CHO cells were stably co-transfected with a heavy chain expressing plasmid, pFUSE-Lucia-TNF-CHIg-hA2m1 (TNF-CHIg-hA2m1) or pFUSE-Lucia-TNF-CHIg-hG1 (TNF-CHIg-hG1) and a light chain expressing plasmid, pFUSE2-TNF-CLIg-hk (TNF-CLIg-hk) to generate Lucia-tagged anti-hTNF-α antibodies, Lucia-anti-hTNF-α-hIgA2m1and Lucia-anti-hTNF-α-hIgG1, of human IgAm2 and human IgG1 isotypes, respectively. pFUSE2-CLIg-hk (CLIg-hk), which expresses no VL, and pSELECT-blasti-mcs (mcs) were used as negative controls. Supernatants
were collected and the luciferase levels determined using QUANTI-Luc™. Only the cells co-producing a Lucia-anti-hTNF-α heavy-chain and an anti-hTNF-α light chain displayed luciferase activity.
3- Neutralizing activity of anti-hTNF-a antibodies
The activity of anti-hTNF-α-hIgA2m1 and Lucia-anti-hTNF-α-hIgA2m1 antibodies, purified from the supernatants of CHO transfected cells, was determined by performing an TNF-α neutralizing assay. Both antibodies display similar neutralizing activities, thus fusion of the Lucia luciferase tag at the N-terminus of the heavy chain does not alter the functionality of the antibody.Back to the top