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Isolation and characterization of a cDNA and gene coding for a fourth CD1 molecule
S P Balk1, P A Bleicher, C Terhorst
1Laboratory of Molecular Immunology, Dana-Farber Cancer Institute, Boston, MA 02115.
Summary
Researchers identified a fourth CD1 molecule, CD1d, in human thymocytes. This discovery expands the CD1 family, revealing its evolutionary relationship to MHC class I molecules and distinct interaction potentials.
Area of Science:
- Immunology
- Molecular Biology
- Genetics
Background:
- The CD1 locus encodes major histocompatibility complex (MHC)-like glycoproteins involved in immune responses.
- Three CD1 molecules (CD1a, CD1b, CD1c) are known, expressed on thymocytes and Langerhans cells.
- These molecules associate with beta 2-microglobulin.
Purpose of the Study:
- To isolate and characterize a novel CD1 molecule from human thymocytes.
- To determine the nucleotide sequence and genomic organization of this new CD1 molecule.
- To compare the structure and potential function of the new CD1 molecule with known CD1 family members and MHC class I molecules.
Main Methods:
- CDNA isolation from a human thymocyte library.
- Nucleotide sequencing.
- Genomic organization analysis.
- Sequence comparison with known CD1 and MHC class I molecules.
Main Results:
- A cDNA coding for a fourth CD1 molecule, designated CD1d, was isolated.
- The complete nucleotide sequence and genomic organization of CD1d were determined.
- CD1d shares structural similarities with CD1a, CD1b, CD1c, and MHC class I molecules.
- CD1d exhibits significant divergence in the alpha 1 and alpha 2 domains compared to other CD1 molecules.
- High homology was observed in the alpha 3 domain, suggesting conserved beta 2-microglobulin binding.
Conclusions:
- CD1d represents a new member of the human CD1 family.
- The structural divergence of CD1d may indicate distinct functional roles.
- The evolutionary relationship between CD1 and MHC class I molecules suggests specialized interactions with cell surface proteins.