Expression, purification, and biochemical characterization of the amino- terminal extracellular domain of the human calcium receptor

Paul K. Goldsmith, Gao Feng Fan, Kausik Ray, Joseph Shiloach, Peter McPhie, Kimberly V. Rogers, Allen M. Spiegel

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56 Scopus citations


We purified the extracellular domain (ECD) of the human calcium receptor (hCaR) from the medium of HEK-293 cells stably transfected with a hCaR cDNA containing an isoleucine 599 nonsense mutation. A combination of lectin, anion exchange, and gel permeation chromatography yielded milligram quantities of >95% pure protein from 15 liters of starting culture medium. The purified ECD ran as an ~78-kDa protein on SDS-polyacrylamide gel electrophoresis and was found to be a disulfide-linked dimer. Its NH2- terminal sequence, carbohydrate content, and CD spectrum were defined. Tryptic proteolysis studies showed two major sites accessible to cleavage. These studies provide new insights into the structure of the hCaR ECD. Availability of purified ECD protein should permit further structural studies to help define the mechanism of Ca2+ activation of this G protein-coupled receptor.

Original languageEnglish (US)
Pages (from-to)11303-11309
Number of pages7
JournalJournal of Biological Chemistry
Issue number16
StatePublished - Apr 16 1999


ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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