The Cytoplasmic Region of Mouse FcRIIb1, but Not FcRIIb2, Binds
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- 作者：Lixin Chen ; Gary J. Pielak ; and Nancy L. Thompson
- 刊名：Biochemistry
- 出版年：1999
- 出版时间：February 16, 1999
- 年：1999
- 卷：38
- 期：7
- 页码：2102 - 2109
- 全文大小：76K
- 年卷期：v.38,no.7(February 16, 1999)
- ISSN：1520-4995
文摘
The cytoplasmic regions of the mouse low-affinity Fc
RII isoforms, FcRIIb1 and FcRIIb2,play key roles in signal transduction by mediating different cellular functions. The FcRIIb1 (94 residues)and FcRIIb2 (47 residues) cytoplasmic regions are generated by differential mRNA splicing in which asingle aspartic acid residue in FcRIIb2 is replaced by a 48-residue insert in FcRIIb1. In previous work,quantities of the mFcRIIb1 and mFcRIIb2 cytoplasmic regions were generated, and their secondarystructures were examined in different solutions with circular dichroism [Chen, L., Thompson, N. L., andPielak, G. J. (1997) Protein Sci. 6, 1038-1046]. In the work described here, steady-state light scatteringwas used to investigate possible interactions of the two isolated cytoplasmic regions with phospholipidvesicles. Three phospholipid compositions were examined: phosphatidylserine/phosphatidylcholine (PS/PC) (25/75, mol/mol); phosphatidylinositol bisphosphate/phosphatidylcholine (PIP2/PC) (25/75, mol/mol);and pure phosphatidylcholine (PC). Binding was examined in the presence and absence of Ca2+. ThemFcRIIb1 cytoplasmic peptide binds PS/PC vesicles weakly in the absence of Ca2+ and more stronglyin the presence of Ca2+. For PIP2/PC vesicles, the behavior is reversed; binding is weak in the presenceof Ca2+ and stronger in its absence. The mFcRIIb1 peptide also weakly binds pure PC vesicles, in aCa2+-independent manner. The mFcRIIb2 cytoplasmic peptide does not bind, in the presence or absenceof Ca2+, to PS/PC, PIP2/PC, or PC vesicles. The implications of these results for the mechanisms ofsignal transduction mediated by the two mFcRII cytoplasmic regions are discussed.
RII isoforms, FcRIIb1 and FcRIIb2,play key roles in signal transduction by mediating different cellular functions. The FcRIIb1 (94 residues)and FcRIIb2 (47 residues) cytoplasmic regions are generated by differential mRNA splicing in which asingle aspartic acid residue in FcRIIb2 is replaced by a 48-residue insert in FcRIIb1. In previous work,quantities of the mFcRIIb1 and mFcRIIb2 cytoplasmic regions were generated, and their secondarystructures were examined in different solutions with circular dichroism [Chen, L., Thompson, N. L., andPielak, G. J. (1997) Protein Sci. 6, 1038-1046]. In the work described here, steady-state light scatteringwas used to investigate possible interactions of the two isolated cytoplasmic regions with phospholipidvesicles. Three phospholipid compositions were examined: phosphatidylserine/phosphatidylcholine (PS/PC) (25/75, mol/mol); phosphatidylinositol bisphosphate/phosphatidylcholine (PIP2/PC) (25/75, mol/mol);and pure phosphatidylcholine (PC). Binding was examined in the presence and absence of Ca2+. ThemFcRIIb1 cytoplasmic peptide binds PS/PC vesicles weakly in the absence of Ca2+ and more stronglyin the presence of Ca2+. For PIP2/PC vesicles, the behavior is reversed; binding is weak in the presenceof Ca2+ and stronger in its absence. The mFcRIIb1 peptide also weakly binds pure PC vesicles, in aCa2+-independent manner. The mFcRIIb2 cytoplasmic peptide does not bind, in the presence or absenceof Ca2+, to PS/PC, PIP2/PC, or PC vesicles. The implications of these results for the mechanisms ofsignal transduction mediated by the two mFcRII cytoplasmic regions are discussed.