Isolation and characterization of CAB-63, a novel calcium-binding protein.
Year: 1985
Type: article
Abstract: A novel calcium-binding protein named CAB-63 (formerly called calregulin) has been purified from bovine liver 100,000 X g supernatant. The purified protein has been characterized with respect to its physical, chemical, and calcium-binding properties. It has an apparent molecular weight of 63,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 55,000 by sedimentation equilibrium centrifugation under nondenaturing conditions. It is an asymmetric molecule with a frictional coefficient of 1.69 and a Stokes radium of 44.2 A. Amino acid analysis has revealed 34.0% acidic residues, 14.0% basic residues, and 4.0% tryptophan. The acidic nature of the molecule is further confirmed by its isoelectric point of 4.65. In the presence of 3 mM MgCl2 and 150 mM KCl, CAB-63 binds 3.0 mol of calcium/mol of protein with an apparent Kd = 0.1 microM. Immunoblotting and Ouchterlony double-diffusion procedures have identified CAB-63 in a variety of bovine tissues. Immunocytochemical staining of both fibroblasts and cryotome-sectioned bovine liver further indicates that CAB-63 immunoreactivity is restricted to an elaborate system of perinuclear membranous vacuoles and cisternae indistinguishable from immunocytochemical staining of the endoplasmic reticulum. It is concluded that CAB-63 represents a major calcium-binding protein whose subcellular organization suggests a possible role in the function of the endoplasmic reticulum.
Source: Journal of Biological Chemistry
Authors: D M Waisman, B P Salimath, M J Anderson
Institution: University of Calgary
Language: English
Topic: S100 Proteins and Annexins
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $3,430
OpenAlex ID: W1567855625