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Structure of chicken plasma retinol-binding protein
G Zanotti1, V Calderone, M Beda
1Department of Organic Chemistry, University of Padua and Biopolymer Research Center, CNR, Padua, Italy. giuseppe.zanotti@unipd.it
Biochimica Et Biophysica Acta
|December 12, 2001
Summary
The crystal structure of chicken retinol-binding protein (RBP) was determined, revealing a close resemblance to mammalian RBP structures. A distinctively defined loop in chicken RBP may influence retinol binding.
Area of Science:
- Structural Biology
- Biochemistry
- X-ray Crystallography
Background:
- Retinol-binding protein (RBP) is crucial for transporting retinol (Vitamin A) in the bloodstream.
- Understanding RBP structure provides insights into vitamin A transport and metabolism.
- Previous studies have characterized mammalian RBP structures.
Purpose of the Study:
- To determine the crystal structure of chicken retinol-binding protein (RBP).
- To compare the structure of avian RBP with known mammalian RBP structures.
- To identify structural differences and their potential functional implications.
Main Methods:
- Purification of retinol-binding protein (RBP) from chicken plasma.
- X-ray crystallography to determine the three-dimensional crystal structure.
- Analysis of structural features and comparison with mammalian RBP structures.
Main Results:
- The crystal structure of chicken holoRBP was determined in space group P2(1)2(1)2(1).
- Chicken holoRBP shares a high overall structural similarity with mammalian holoRBPs.
- A loop (residues 63-67) near the retinol-binding site is better defined in chicken RBP compared to mammalian RBPs, despite the absence of C-terminal residues found in mammals.
Conclusions:
- Phylogenetic distance does not prevent structural conservation in RBP.
- The C-terminal residues present in mammalian RBP are not essential for overall structural integrity.
- The improved definition of loop 63-67 in avian RBP may represent an adaptation for retinol binding or stability.