New methods for creating and detecting specific proteins

In their native form, the thousands of assorted proteins in our body are virtually indistinguishable.

Scientists who want to examine the properties and functions of specific proteins, as well as the activities of individual genes, must rely on chemical tags to manipulate and visualize them. This month's release of Cold Spring Harbor Protocols highlights methods for creating and detecting specific proteins, as well as for characterizing the activities of specific genes during embryonic development. Two of the methods are freely available online.

One of the freely available methods describes how to attach a small tag, called GST (glutathione- S -transferase), to a specific protein of interest. This is accomplished by growing bacteria that contain the DNA sequence for the GST tag adjacent to the gene for the protein of interest. When the bacteria grow, they express the "GST fusion protein," which consists of a GST tag attached to the desired protein. Using a chemical (glutathione) that binds specifically to GST, the GST fusion proteins can be easily sequestered and studied in more detail.

To test the activity of a certain gene during embryonic development, mice can be engineered to produce a "reporter" protein called -galactosidase, which functions as a proxy for the protein normally produced by the gene of interest. The second freely available method describes a strategy for staining transgenic mouse embryos engineered to express the -galactosidase protein. Once stained, the tissues with -galactosidase produce a brilliant blue pigment, allowing researchers to visualize where and when a gene of interest is expressed during embryonic development.