Describe and give the results of a yeast two-hybrid assay...

Name: Problem 26, Chapter 14: Molecular Biology
Uploaded: 2021-11-20T14:51:42-08:00
Duration: 3 min 48 s
Channel: Rabeya Zahid
Description: Describe and give the results of a yeast two-hybrid assay that shows interaction between yeast branchpoint bridging protein (BBP) and two other proteins. What are the two other proteins, and where are they found with respect to the ends of the intron in the commitment complex?

Describe and give the results of a yeast two-hybrid assay that shows interaction between yeast branchpoint bridging protein (BBP) and two other proteins. What are the two other proteins, and where are they found with respect to the ends of the intron in the commitment complex?

Key Concepts

Protein Localization in Intron Definition

In the commitment complex, proteins are strategically positioned along the intron to define its boundaries. One key interaction involves a protein (often exemplified by Mud2 in yeast) that associates with BBP near the branchpoint region, while another interaction involves a protein that is part of or associated with the U1 snRNP complex at the 5? splice site. This spatial separation – with one partner near the branchpoint and the other at the 5? end – is vital for linking the two ends of the intron and ensuring that the splicing machinery correctly identifies and processes the intron.

Yeast Two-Hybrid Assay

The yeast two?hybrid assay is a molecular technique used to detect physical interactions between two proteins in vivo. It works by fusing proteins of interest to separate domains of a transcription factor; if the two proteins interact, the transcription factor is reconstituted and drives expression of a reporter gene. This assay provides a relatively simple and effective means of mapping protein–protein interactions within cells.

Spliceosome Commitment Complex

The commitment complex, sometimes referred to as the early (E) complex, is an early assembly intermediate in pre?mRNA splicing where key splicing signals are recognized. In this complex the 5? splice site is bound by components of the U1 small nuclear ribonucleoprotein (snRNP) while the branchpoint region is recognized by factors such as the branchpoint binding protein (BBP). The precise organization of these components is critical for correct intron definition and subsequent spliceosome assembly.

Role of Branchpoint Bridging Protein (BBP) and Its Interactions

BBP (Branchpoint Bridging Protein) is essential for recognizing the branchpoint sequence within introns and forming a bridge between the branchpoint and the 5? splice site. Its interaction with specific partner proteins, as revealed by assays such as the yeast two?hybrid system, helps stabilize the commitment complex and facilitates the correct spatial arrangement needed for efficient splicing. Typically, BBP interacts with proteins that are positioned at opposite ends of the intron to form a molecular bridge.

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