The crystal structure of a soluble form of the T lymphocyte antigen CD2 provides the first complete view of the extracellular region of a cell adhesion molecule. The topology of the molecule, which comprises two immunoglobulin-like domains, is the same as that of the first two domains of CD4 but the relative domain orientation is altered by a fairly flexible linker region. The putative ligand-binding beta-sheet forms a flat surface towards the top of the molecule. Crystal contacts between these surfaces suggest a plausible model for the adhesive interaction.
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Amino Acid Sequence, Animals, Antigens, Differentiation, T-Lymphocyte, CD2 Antigens, Cell Adhesion Molecules, Crystallization, Epitopes, Glycosylation, Models, Molecular, Molecular Sequence Data, Peptide Fragments, Protein Structure, Tertiary, Rats, Receptors, Immunologic, X-Ray Diffraction