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Two peptides from CD23, including the inverse RGD sequence and its related peptide, interact with the MHC class II
1Institute of Immunological Science, Graduate School of Environmental Earth Science, Hokkaido University, Kita-15, Nishi-7, Kita-ku, Sapporo, 060-0815, Japan. ochi@imm.hokudai.ac.jp
Biochemical and Biophysical Research Communications
|February 16, 2000
Summary
Researchers synthesized three peptides to study the function of the CD23 molecule. Peptide 3 inhibited L-KT9 cell aggregation and showed affinity for MHC class II molecules, suggesting roles in cell interactions and immune responses.
Area of Science:
- Immunology
- Molecular Biology
- Cell Biology
Background:
- The human CD23 molecule, a low-affinity receptor for IgE, possesses a C-type lectin domain and an Arg-Gly-Asp (RGD) sequence.
- CD23 plays a role in B cell activation and IgE regulation.
- Understanding CD23's molecular interactions is crucial for immunology.
Purpose of the Study:
- To synthesize and evaluate the functions of three peptides related to CD23's structure.
- To investigate the binding affinities of these peptides to CD23 and MHC class II molecules.
- To elucidate the role of CD23 in homotypic cell aggregation and immune responses.
Main Methods:
- Synthesis of three distinct peptides: #1 (inverse RGD), #2 (RGD-binding inhibitory), and #3 (inverse sequence from CD23 N-sugar chain).
- Assessment of peptide inhibition on L-KT9 cell aggregation.
- Use of isotope-labeled peptides to determine binding to MHC class II and CD23 molecules.
Main Results:
- Only peptide 3 effectively inhibited L-KT9 cell aggregation.
- Peptides 1 and 3 both bound to MHC class II molecules.
- Peptide 3 exhibited higher affinity to MHC class II than peptide 1; peptide 1 did not bind to CD23.
Conclusions:
- Peptide 3's inhibition of cell aggregation and its binding to MHC class II suggest significant roles in cellular interactions.
- CD23's interaction with MHC class II and its lectin function in homotypic aggregation are highlighted.
- The study provides insights into the physiological and evolutionary functions of CD23.