User:PJDCRNA/Heterologous expression

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Heterologous expression refers to the expression of a gene or part of a gene in a host organism that does not naturally have this gene or gene fragment. Insertion of the gene in the heterologous host is performed by recombinant DNA technology. Most frequently, this is utilized to evaluate the specific interactions between proteins or to identify the functional effects of introducing amino acid mutations in proteins. For instance, it is widely used to analyze the molecular mechanisms of ion channel function and modification.

Methods
Techniques to isolate specified genes: Gene identification using computer-based methods is known as a heterologous screening technique. However, due to faulty membrane protein purification, this approach makes it difficult to separate genes in every aspect. Another approach to isolating membrane proteins uses a technique known as radiolabeled ligands or inhibitors.

Techniques to incorporate genes into the host: Gene gun delivery, Electroporation, Viral transduction, and Lipofection.

Gene gun delivery works on the principle of the bombardment of genes coated with metal particles. and is used mostly in plants.

Electroporation is a method that uses high voltage to create pores in the cell membranes of mammalian cells.

Viral transduction uses viral vectors and is used for the stable introduction of genes into the target cells.

Lipofection method is used to inject the gene into a cell with the help of liposomes.

After being inserted in the host, the gene may be integrated into the host DNA, causing permanent expression, or not integrated, causing transient expression. Heterologous expression can be done in many types of host organisms. Genes are subjected to heterologous expression often to study specific protein interactions. E. coli, yeast (S. cerevisiae, P. pastoris), immortalized mammalian cells, insects (Spodoptera frugiperda), frogs (Xenopus laevis), and amphibian oocytes (i.e. unfertilized eggs) are commonly used for studies that require heterologous expression. However, membrane proteins like transporters and channels are better expressed in mammalian cell lines as the proper function of these proteins frequently requires post-translational changes that can fully occur in mammalian cells (e.g. glycosylation, isoprenylation, and deamidation)