Spring Break
Genetic method helps
Issue date: 10/2/08
Proteins are one of the essential building blocks of biological systems, but with as many as 100,000 proteins in the human body alone, isolating, purifying and characterizing them is no small feat.
In a collaboration among experts at Hopkins, Georgetown and Harvard, molecular biologists have developed a way to add antibody-binding regions to specific proteins in their natural cellular environment. Antibodies that correspond only with this extra region bind to it and tag the protein, allowing scientists to track the protein inside cells and tissues.
"This is an especially useful approach when studying a newly-discovered protein to which antibodies are as yet unavailable," senior researcher Todd Waldman said.
Waldman, who received his M.D. and Ph.D. degrees at Hopkins, is currently on faculty at Georgetown. Ultimately, these tagged proteins then can be easily purified and visualized using microscopes to study their structural and biological properties.
Tagging proteins involves attaching a small segment of DNA to the gene that codes for the protein of interest. This segment adds a chain of about 10 additional amino acids to the gene, which is then "read," and protein is synthesized.
This added chain is called an epitope. Scientists can combine these modified proteins with antibodies, which will bind specifically with the epitope and act as molecular flags. And voilĂ ! One tagged protein ready for action.
However, where this happens is the difference between the routine and the impossible, until now. "One important disadvantage to the standard, commonly used epitope tagging approach has been that it could only be applied to proteins whose gene had been cloned," Waldman said.
In this study, recombinant DNA was used to insert the epitope-coding DNA into genes in their natural chromosomal location, or endogenous genes. Therefore, human proteins can be tagged in their normal genetic environment.
This technique avoids the limitations found in cloning, where the expression and transcription of the cloned gene cannot be well-regulated. In cloning techniques, genes are modified in cultured cells and then transplanted back into an animal or plant. The new approach allows natural cellular processes to take care of the regulation themselves.
In a collaboration among experts at Hopkins, Georgetown and Harvard, molecular biologists have developed a way to add antibody-binding regions to specific proteins in their natural cellular environment. Antibodies that correspond only with this extra region bind to it and tag the protein, allowing scientists to track the protein inside cells and tissues.
"This is an especially useful approach when studying a newly-discovered protein to which antibodies are as yet unavailable," senior researcher Todd Waldman said.
Waldman, who received his M.D. and Ph.D. degrees at Hopkins, is currently on faculty at Georgetown. Ultimately, these tagged proteins then can be easily purified and visualized using microscopes to study their structural and biological properties.
Tagging proteins involves attaching a small segment of DNA to the gene that codes for the protein of interest. This segment adds a chain of about 10 additional amino acids to the gene, which is then "read," and protein is synthesized.
This added chain is called an epitope. Scientists can combine these modified proteins with antibodies, which will bind specifically with the epitope and act as molecular flags. And voilĂ ! One tagged protein ready for action.
However, where this happens is the difference between the routine and the impossible, until now. "One important disadvantage to the standard, commonly used epitope tagging approach has been that it could only be applied to proteins whose gene had been cloned," Waldman said.
In this study, recombinant DNA was used to insert the epitope-coding DNA into genes in their natural chromosomal location, or endogenous genes. Therefore, human proteins can be tagged in their normal genetic environment.
This technique avoids the limitations found in cloning, where the expression and transcription of the cloned gene cannot be well-regulated. In cloning techniques, genes are modified in cultured cells and then transplanted back into an animal or plant. The new approach allows natural cellular processes to take care of the regulation themselves.
Be the first to comment on this story