Different cation binding to the I domains of alpha1 and alpha2 integrins: implication of the binding site structure.
In the present work, we studied the interactions of recombinant alpha1 and alpha2 integrin I domains with cations Tb(3+), Mn(2+), Mg(2+) and Ca(2+). We observed that alpha1 and alpha2 I domains bind these cations with significantly different characteristics. The binding of Mg(2+) by the alpha1 I domain was accompanied by significant changes of tryptophan fluorescence which could be interpreted as a conformational change. Comparison of the alpha1 integrin I domain structure obtained by comparative modeling with a known structure of the alpha2 integrin I domain shows distinct differences in the metal ion binding sites which could explain the differences in cation binding.
Obsil
T
T
Department of Physical and Macromolecular Chemistry, Faculty of Sciences, Charles University, Hlavova 8/2030, 128 40, Prague, Czech Republic. obsil@biomed.cas.cz
Hofbauerová
K
K
Amler
E
E
Teisinger
J
J
D000595:Amino Acid Sequence; D015703:Antigens, CD / Q000737:chemistry* / Q000378:metabolism*; D001665:Binding Sites; D002412:Cations / Q000378:metabolism*; D005453:Fluorescence; D039423:Integrin alpha1; D039421:Integrin alpha2; D008274:Magnesium / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013725:Terbium / Q000378:metabolism; D014364:Tryptophan / Q000737:chemistry
D015703:Antigens, CD; D002412:Cations; D039423:Integrin alpha1; D039421:Integrin alpha2; D011994:Recombinant Proteins; D013725:Terbium; D014364:Tryptophan; D008274:Magnesium