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Cell. 1993 Mar 26;72(6):857-67.

A novel divalent cation-binding site in the A domain of the beta 2 integrin CR3 (CD11b/CD18) is essential for ligand binding.

Author information

1
Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown 02129.

Abstract

A recombinant peptide encoding the CD11b A domain bound 54Mn2+ with a high affinity. Other divalent cations, including Mg2+, Zn2+, Ni2+, Co2+, and Cd2+, but not Ca2+ or Ba2+, competed effectively for Mn2+ binding. Amino acid substitutions within two conserved and noncontiguous regions in the recombinant peptide abolished 54Mn2+ binding. When these substitutions were introduced independently in complement receptor type 3 (CR3), each abolished the metal-dependent binding of the receptor to the major C3 opsonin iC3b, without impairing subunit association or surface expression of the receptor. These findings identify an unsuspected and novel metal-binding site within the A domain of CR3 that is required for metal-dependent ligand binding and also identify a good target for designing drugs aimed at countering the inflammatory potential of this key receptor.

PMID:
8458080
DOI:
10.1016/0092-8674(93)90575-b
[Indexed for MEDLINE]

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