AscentGene Complete Protein Services

       Active and purified recombinant proteins have been widely used for the identification of biomarkers, characterization of protein functions, discovery of drug targets, and many other applications. Each protein has a different amino acid composition, size, activity, and unique characteristics. Therefore, unlike DNA, each step of protein expression or purification is an art of technology which needs special handling and requires experience and expertise in molecular biology, cell biology, biochemistry and thorough knowledge of protein function.

       With more than 25 years of experience in the field, AscentGene provides our customers with Complete Protein Services (CPS), including subcloning, protein expression, protein purification and protein assays. Our protein products have been utilized for high throughput screen (HTS) assays, biomarker identification, antibody production, structural and functional studies, development of diagnostic devices, and much more.

1. Subcloning

   Purchase commercially available cDNA clone(s) from our partners or synthesize new genes on demand. Help customer choose the proper expression vector depending on protein’s size, solubility, cell localization, functionality, post-translational modification and purpose of the project. Design expression construct with a proper tag sequence (6His, Flag, HA, GST, MBP, c-Myc, GFP, Biotin, etc). Insert the gene of interest (GOI) into the vector. Sequencing analysis to confirm the GOI.

2. Protein expression

   E. coli system      Expression of a protein in E. coli cells is the most convenient, quickest and most cost-effective method to obtain a large amount of protein.      Approximately 60-70% of human proteins can be expressed in E coli and be functionally active.      However, E coli cells lack many enzymes for post-translational modifications, such as phosphorylation, glycosylation and acetylation.      Modification by these enzymes is essential for certain types of proteins, including cytokines, nuclear hormone receptors, protein kinases and other regulatory proteins.      The turn-around time is 1-2 weeks. Baculovirus system      Expressing protein in a baculovirus system is the primary choice if post-translational modification is essential for the activity of the protein of interest.      More than 95% of human proteins can be expressed in baculovirus and function properly.      Three different host cell lines are currently used, including Sf9, Sf21 and HighFive cells.      The turn around time is 3-6 weeks. Mammalian system      The mammalian system has certain advantages for proteins with solubility and post-translational modification problems, as well as those that need to be used for cell function studies.      In addition, because many mammalian cell lines are available at AscentGene, scientists have the option to study specific gene function in a specific cell line.      However, expression in mammalian systems requires longer turn-around time and has higher cost.      We provide services for protein expression in a variety of mammalian cells (HeLa, HEK293, CHO, NIH3T3, SH-SY5Y, MCF7, MDA231, MDA468, etc).      Development of stable cell lines or transient transfection is achievable for most mammalian cell lines.      The turn-around time is 4-12 weeks.

3. Protein purification

   Depending on the type, size, solubility, tag sequence, expression system, quantity and quality of the protein requested, we combine conventional and FPLC technologies, including affinity, anion/cation exchange or hydrophobic interaction chromatography and gel filtration, to guarantee the final protein product with >90% homogeneity. The turn-around time is 1-3 weeks.

    

4. Protein identification

   In addition to the services for purification of over-expressed proteins derived from exogenously induced genes,      we purify endogenous proteins from mammalian sources (cell lines, tissues, etc) for protein identification       (Protein ID) purposes. The turn-around time is 1-4 weeks.