Protein Expression

In protein research, protein expression refers to the production of proteins using cells that have been engineered with recombinant DNA technology to produce large quantities of a desired protein. The starting point for protein expression is a known amino acid sequence of the desired protein.

Protein Expression Steps

  1. Starting with a desired protein amino acid sequence, reverse-translate into a DNA sequence
  2. Employ artificial gene synthesis (a.k.a. Gene printing) to produce DNA
  3. Insert DNA vector into host cells, usually E. coli, and usually by opening pores in the bacterial cell via heat shock
  4. Make a starter culture for protein expression
  5. Batch and increase production
  6. Lysis, sonication and other techniques to release the proteins from the cells
  7. Protein Purification

What is Protein Mass Spectrometry?

Mass spectrometry studies molecules by measuring the mass of intact molecules and their fragments. In the case of Protein Mass Spectrometry the molecules in question are proteins, or more likely peptides digested from proteins. The mass of these proteins, peptides and fragments thereof can be used to determine the identity and sequence of a protein or peptide.

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Antibody Protein Expression

Antibody Protein Expression is a special case of protein expression that produces Antibody proteins. The antibodies resulting from Antibody Expression are often called monoclonal antibodies (mAb), since they are all cloned and should all be identical in sequence. Antibodies can of course be produced from Hybridoma, but mAb have advantages.

Protein Sequencing followed by Expression

In some research or pharmaceutical applications, it is necessary to express or produce more of a protein or antibody sample, but the DNA sequence of the protein/antibody is not yet known. In other cases, the sequence of the protein or antibody is only partially known with confidence. In these cases, Protein de novo Sequencing can be used to determine the sequence of the protein or antibody directly from the sample without reference to a DNA sequence, thus enabling expression.

Sequencing to Reducing the Cost and Complexity of Protein Expression

If the sequence of a desired protein or antibody is not fully known prior to expression, this can result in prohibitive time and materials costs to express, purify and concentrate the right protein for downstream use.

For instance, if one amino acid could be swapped for another, researchers would have to express two variants of the protein or antibody. Downstream testing would confirm which sequence produced the protein or antibody with the desired characteristics. If two amino acids could be swapped, this would result in 4 combinations to be expressed and tested. Three amino acids swapped could mean 15 sequences to express and test.

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