High performance liquid chromatography of the 1,25-dihydroxyvitamin D3 receptor: its application toward resolution of receptor-monoclonal antibody complexes

Examination and rapid analysis of hepatic cytosolic receptors for 2,3,7,8-tetrachlorodibenzo-p-dioxin using gel-permeation high performance liquid chromatography

Gel-permeation high performance liquid chromatography was used to examine the molecular characteristics of the cytosolic and nuclear receptors for 2,3,7,8-tetrachlorodibenzo-p-dioxin. The physical properties for this receptor previously established by sucrose-density gradient analysis have been maintained by the technique. The high performance liquid chromatography method offers the advantages of rapid separation and reproducibility thus minimizing possible effects of proteolytic enzymes or dissociation of the ligand-receptor complex. The specific binding of [3H]2,3,7,8-tetrachlorodibenzo-p-dioxin as measured by this system also corresponds quantitatively to that determined by the hydroxyapatite method. These methods will facilitate a further understanding of the biochemical actions of 2,3,7,8-tetrachlorodibenzo-p-dioxin and related compounds, as well as an understanding of the physiological function of this receptor molecule.

High pressure liquid chromatographic detection of intracellular retinoid binding proteins from cultured cell and tumor cytosols

We report the first application of high pressure liquid chromatography (HPLC) in the rapid detection of cellular retinoic acid binding protein (CRABP) and cellular retinol binding protein (CRBP). Cytosols from cultured cells (3T6 and MCF-7) or from tumors (melanoma and ovarian) were labeled with [3H]retinoic acid (30 Ci/mmol) and [3H]retinol (43 Ci/mmol) and analyzed via HPLC employing a 60 cm TSK 3000 sw column. In each case CRABP and CRBP were readily detectable at an elution volume of 22.5 ml, consistent with their molecular weights of 14,600. Identity of the binding protein peaks was established by saturability, specificity, and selective inhibition of binding by an organomercurial. Thus, this method, which resolves CRABP and CRBP in crude mixtures from the majority of cytosolic proteins, should be a valuable tool in the evaluation of vitamin A-binding protein interactions and their biological significance.

Purification of the receptor for 1 alpha,25-dihydroxyvitamin D3 from chicken intestine

Methods were investigated for use in the purification of the chicken intestinal receptor for 1 alpha,25-dihydroxyvitamin D3. The techniques investigated include column isoelectric focusing, gel exclusion, polyacrylamide gel electrophoresis, and DNA-cellulose, DEAE-cellulose, and hydroxylapatite chromatography. For the starting receptor preparation, a nuclear extract of chicken intestinal mucosa was found to be enriched above cytosol preparations and a plentiful source of receptor. A five-step purification scheme that resulted in the purification of the receptor protein by 5800-fold with 8% yield has been described. Analysis of the purified proteins on polyacrylamide gel electrophoresis containing sodium dodecyl sulfate suggests homogeneity. Analysis using two-dimensional polyacrylamide electrophoresis characterized the purified protein as having a molecular weight of approximately 63 000 and a pI of 6.0-6.2. Furthermore, assessment of protein purity by 125I iodination followed by sucrose gradient analysis revealed that approximately 90% of the iodinated macromolecules have the same sedimentation coefficient as the titrated 1 alpha,25-dihydroxyvitamin D3 receptor complex. The final purified receptor that bound tritiated 1 alpha,25-dihydroxyvitamin D3 retained affinity for DNA-cellulose and possesses a 3.7S sedimentation coefficient. The receptor has an estimated Stokes radius of 37 A.