Abstract
IgE-binding protein (εBP) was originally identified by virtue of its affinity for IgE. It is now known to be a β-galactoside-binding lectin with the characteristic of an S-type carbohydrate recognition domain. The protein is composed of two domains: the amino-terminal domain consisting of tandem repeats and the carboxyl-terminal domain containing sequences shared by other S-type carbohydrate recognition domains. The amino-terminal domain also contains a number of potential recognition sites for collagenase cleavage. In this study, human εBP was first expressed in Escherichia coli, and the carboxyl-terminal domain (εBP-C) was then generated by collagenase digestion of εBP. By equilibrium dialysis, the association constants of εBP and εBP-C for lactose were found to be similar (6.0 ± 0.70) x 104 M-1 and (4.7 ± 0.27) x 104 M-1, respectively. Both polypeptides contain only one lactose-binding site/molecule. By an assay involving binding of 125I-labeled eBP or εBP-C to solid phase IgE, and inhibition of this binding by saccharides, it was determined that εBP-C retains the saccharide specificity of εBP. Importantly, although unlabeled εBP-C inhibited the binding of the radiolabeled εBP to IgE, unlabeled εBP caused increased binding to IgE, suggesting self-association among εBP molecules. Oligomeric structures resulting from self-association of εBP were confirmed by chemical cross-linking studies. Furthermore, εBP possesses hemagglutination activity on rabbit erythrocytes, whereas εBP-C lacks such activity. Based on these results, we propose a structural model for multivalency of εBP: dimerization or oligomerization of εBP occurs through intermolecular interaction involving the amino-terminal domain.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 14167-14174 |
| Number of pages | 8 |
| Journal | Journal of Biological Chemistry |
| Volume | 267 |
| Issue number | 20 |
| State | Published - Jul 15 1992 |
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ASJC Scopus subject areas
- Biochemistry
Cite this
Biochemical and biophysical characterization of human recombinant IgE-binding protein, an S-type animal lectin. / Hsu, Daniel K.; Zuberi, Riaz I.; Liu, Fu-Tong.
In: Journal of Biological Chemistry, Vol. 267, No. 20, 15.07.1992, p. 14167-14174.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Biochemical and biophysical characterization of human recombinant IgE-binding protein, an S-type animal lectin
AU - Hsu, Daniel K.
AU - Zuberi, Riaz I.
AU - Liu, Fu-Tong
PY - 1992/7/15
Y1 - 1992/7/15
N2 - IgE-binding protein (εBP) was originally identified by virtue of its affinity for IgE. It is now known to be a β-galactoside-binding lectin with the characteristic of an S-type carbohydrate recognition domain. The protein is composed of two domains: the amino-terminal domain consisting of tandem repeats and the carboxyl-terminal domain containing sequences shared by other S-type carbohydrate recognition domains. The amino-terminal domain also contains a number of potential recognition sites for collagenase cleavage. In this study, human εBP was first expressed in Escherichia coli, and the carboxyl-terminal domain (εBP-C) was then generated by collagenase digestion of εBP. By equilibrium dialysis, the association constants of εBP and εBP-C for lactose were found to be similar (6.0 ± 0.70) x 104 M-1 and (4.7 ± 0.27) x 104 M-1, respectively. Both polypeptides contain only one lactose-binding site/molecule. By an assay involving binding of 125I-labeled eBP or εBP-C to solid phase IgE, and inhibition of this binding by saccharides, it was determined that εBP-C retains the saccharide specificity of εBP. Importantly, although unlabeled εBP-C inhibited the binding of the radiolabeled εBP to IgE, unlabeled εBP caused increased binding to IgE, suggesting self-association among εBP molecules. Oligomeric structures resulting from self-association of εBP were confirmed by chemical cross-linking studies. Furthermore, εBP possesses hemagglutination activity on rabbit erythrocytes, whereas εBP-C lacks such activity. Based on these results, we propose a structural model for multivalency of εBP: dimerization or oligomerization of εBP occurs through intermolecular interaction involving the amino-terminal domain.
AB - IgE-binding protein (εBP) was originally identified by virtue of its affinity for IgE. It is now known to be a β-galactoside-binding lectin with the characteristic of an S-type carbohydrate recognition domain. The protein is composed of two domains: the amino-terminal domain consisting of tandem repeats and the carboxyl-terminal domain containing sequences shared by other S-type carbohydrate recognition domains. The amino-terminal domain also contains a number of potential recognition sites for collagenase cleavage. In this study, human εBP was first expressed in Escherichia coli, and the carboxyl-terminal domain (εBP-C) was then generated by collagenase digestion of εBP. By equilibrium dialysis, the association constants of εBP and εBP-C for lactose were found to be similar (6.0 ± 0.70) x 104 M-1 and (4.7 ± 0.27) x 104 M-1, respectively. Both polypeptides contain only one lactose-binding site/molecule. By an assay involving binding of 125I-labeled eBP or εBP-C to solid phase IgE, and inhibition of this binding by saccharides, it was determined that εBP-C retains the saccharide specificity of εBP. Importantly, although unlabeled εBP-C inhibited the binding of the radiolabeled εBP to IgE, unlabeled εBP caused increased binding to IgE, suggesting self-association among εBP molecules. Oligomeric structures resulting from self-association of εBP were confirmed by chemical cross-linking studies. Furthermore, εBP possesses hemagglutination activity on rabbit erythrocytes, whereas εBP-C lacks such activity. Based on these results, we propose a structural model for multivalency of εBP: dimerization or oligomerization of εBP occurs through intermolecular interaction involving the amino-terminal domain.
UR - http://www.scopus.com/inward/record.url?scp=0026770786&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0026770786&partnerID=8YFLogxK
M3 - Article
VL - 267
SP - 14167
EP - 14174
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 20
ER -