Stereospecific mobilization of intracellular Ca2+ by inositol 1,4,5-triphosphate. Comparison with inositol 1,4,5-trisphosphorothioate and inositol 1,3,4-trisphosphate. |
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Authors: | J Strupish A M Cooke B V Potter R Gigg and S R Nahorski |
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Institution: | Departament de Bioquimica i Biologia Molecular (Unitat de Ciències), Universitat Autònoma de Barcelona, Spain. |
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Abstract: | The isolated activation segment of pig procarboxypeptidase A binds two Tb3+ ions in a strong and specific way. In contrast, the binding of Ca2+, Cd2+ and Mg2+ is weak. The binding of Tb3+ increases the resistance of the isolated activation segment against proteolysis and competes for the binding of the carbocyanine dye Stains-All. This dye forms complexes with the activation segment showing spectral properties similar to those observed with EF-hand structures. The presented results support a previous hypothesis on the existence of two regions in the activation segment of pancreatic procarboxypeptidases structurally related to Ca2+-binding domains of the EF-hand protein family. |
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