Publication Abstract from PubMed
The integrin alpha X beta 2 (CD11c/CD18, p150,95) binds ligands through the I domain of the alpha X subunit. Ligands include the complement factor fragment iC3b, a key component in the innate immune defense, which, together with the expression of alpha X beta 2 on dendritic cells and on other leukocytes, suggests a role in the immune response. We now report the structure of the alpha X I domain resolved at 1.65 A by x-ray crystallography. To analyze structural requirements for ligand binding we made a mutation in the alpha X I domain C-terminal helix, which increased the affinity for iC3b approximately 200-fold to 2.4 microM compared with the wild-type domain affinity of approximately 400 microM. Gel permeation chromatography supported a conformational change between the wild-type and mutated domains. Conservation of allosteric regulation in the alpha X I domain points to the functional importance of this phenomenon.
Structure and allosteric regulation of the alpha X beta 2 integrin I domain.,Vorup-Jensen T, Ostermeier C, Shimaoka M, Hommel U, Springer TA Proc Natl Acad Sci U S A. 2003 Feb 18;100(4):1873-8. Epub 2003 Jan 28. PMID:12554829[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
