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Published on: July 22, 2016
Xenopus poly(A) binding protein: functional domains in RNA binding and protein-protein interaction
Journal of Molecular Biology
|February 16, 1996
Summary
Xenopus poly-adenylate binding protein (PABP) RNA binding domains (RBDs) show varied RNA affinities. RBDs 1 and 2 match wild-type affinity, while RBDs 3 and 4 contribute to poly(A) organization.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- The Xenopus poly-adenylate binding protein (PABP) plays a crucial role in mRNA regulation.
- PABP contains four RNA binding domains (RBDs) that mediate its interaction with poly(A) tails.
- Understanding the specific contribution of each RBD is essential for elucidating PABP function.
Purpose of the Study:
- To investigate the distinct RNA binding affinities and specificities of individual and combined RNA binding domains (RBDs) of Xenopus PABP.
- To map RNA-protein contacts within the full-length PABP using UV crosslinking.
- To determine the role of the carboxy-terminal non-RBD region in PABP function.
Main Methods:
- Site-directed mutagenesis to generate subsets of RNA binding domains (RBDs).
- RNA binding assays to determine affinity and selectivity of PABP variants.
- UV crosslinking to map RNA-protein interaction sites.
- Analysis of poly(A) organizing activity in vitro.
Main Results:
- RBDs 1 and 2 exhibit RNA binding affinity and selectivity comparable to wild-type PABP.
- RBDs 3 and 4 show altered selectivity and reduced affinity for poly(A) RNA compared to wild-type.
- The carboxy-terminal region does not affect RNA binding but mediates homodimerization.
- RBDs 3 and 4, in conjunction with the C-terminus, confer poly(A) organizing activity.
Conclusions:
- Individual RNA binding domains of Xenopus PABP possess distinct functional properties.
- RBDs 1 and 2 are primarily responsible for high-affinity RNA binding.
- RBDs 3 and 4, along with the C-terminus, are critical for the poly(A) organizing function of PABP, forming ribonucleoprotein complexes.
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