Isolation and partial characterization of a 700 kilodalton human colon carcinoma associated antigen

Cancer Biochem Biophys. 1983;6(4):249-59.


An antigen of high molecular weight (CA-3) was isolated from the cytosol fraction of GW-39 human colon tumor cells by antibody affinity chromatography. CA-3 was characterized by an acidic pI value of 4.5-4.9, a molecular weight of 700 kilodaltons and a sedimentation coefficient of 13S. It contained all of the commonly occurring amino acids and had an acidic to basic amino acid ratio of 1.4. CA-3 was resistant to dissociation by reducing agents as well as by sodium dodecylsulfate. Quantitation of CA-3 by a radioimmunoassay employing rabbit anti-CA-3 antiserum revealed a marked elevation of CA-3 in the cytosol extracts of human primary colon carcinoma in comparison to normal colon. The molecular properties of CA-3 are compared to those of carcinoembryonic antigen, high molecular weight colon specific antigen CSAp and two other high molecular weight proteins, fibronectin and conglutinin. Colon antigen CA-3 appears to be different from these other molecules in terms of its molecular weight, sedimentation value, isoelectric point and amino acid composition.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antigens, Neoplasm / isolation & purification*
  • Carcinoma / immunology*
  • Colonic Neoplasms / immunology*
  • Cricetinae
  • Cytosol / immunology
  • Humans
  • Isoelectric Point
  • Molecular Weight
  • Radioimmunoassay


  • Antigens, Neoplasm