1. Purification and structural characterization of the CD11b/CD18 integrin alpha subunit I domain reveals a folded conformation in solution.
- Author
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Fairbanks MB, Pollock JR, Prairie MD, Scahill TA, Baczynskyj L, Heinrikson RL, and Stockman BJ
- Subjects
- Amino Acid Sequence, Amino Acids analysis, CD18 Antigens isolation & purification, Calcium pharmacology, Circular Dichroism, Escherichia coli genetics, Factor Xa, Glutathione Transferase genetics, Leukocytes chemistry, Macrophage-1 Antigen isolation & purification, Magnesium pharmacology, Magnetic Resonance Spectroscopy, Molecular Sequence Data, Protein Folding, Recombinant Fusion Proteins biosynthesis, Recombinant Fusion Proteins isolation & purification, Sequence Analysis, CD18 Antigens chemistry, Macrophage-1 Antigen chemistry, Protein Conformation drug effects
- Abstract
The alpha subunits of the leukocyte CD11/CD18 integrins contain an approximately 200 amino acid 'inserted' or I domain. The I domain of the cell-surface Mac-1 (CD11b/CD18) integrin has been shown to be the major recognition site for several adhesion ligands, including iC3b, fibrinogen, factor X, and ICAM-1. The I domain from the Mac-1 alpha subunit has been expressed in Escherichia coli as a soluble GST-fusion protein containing a factor Xa sensitive cleavage site. Analytical characterization of the purified I domain reveals that it is obtained in very high quality at high yields. CD and NMR spectra indicate that I domain adopts a predominantly folded structure in solution, independent of the remainder of the alpha subunit. Addition of Ca2+ and Mg2+ did not significantly perturb the structural conformation.
- Published
- 1995
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