Interactions with other proteins

There are several techniques for studying interactions between proteins. Interactions between proteins are very important in control of the cell cycle and the signal transduction pathway. One recently developed technique for identifying is the two-hybrid system that is done in yeast cells but can be used to analyze the proteins of other organisms, including humans. This assay makes use of the fact that activation of transcription by transcription factors requires a DNA binding region (domain) and an activation domain that activates gene transcription. These two domains can function even when present in two different molecules if the two molecules interact.

The question: What protein(s) interact with protein X that you are studying?

1. The gene for protein X is cloned next to a DNA binding domain, creating a fused gene that will produce a hybrid protein.
   
   
2. Random DNA sequences are cloned next to a portion of a gene encoding an activation domain. This creates a library of fused genes with different regions attached to the same activation domain.
   
   
3. The proteinX-DNA binding domain clone is introduced into the cells containing the different sequences attached to the activation domain. If protein X interacts with one of the proteinY portion of the activation domain fusion, transcription will occur because both parts (DNA binding and activation) are now connected.

	Fundamentals of Cell Function
	Cloning DNA
	Libraries
	Screening Libraries
	Gene Expression
	Elimination of Gene
	Interactions with Other Proteins