The Rhesus D antigen. A dicyclohexylcarbodiimide-binding proteolipid.
Previous studies on the human Rhesus D antigen revealed several similarities between the D antigen and proteolipids. Proteolipids are a family of low-molecular-weight, hydrophobic proteins that are soluble in chloroform/methanol. In addition, many proteolipids bind dicyclohexylcarbodiimide (DCCD), an ATPase inhibitor. For determination of whether the D antigen was a proteolipid, the chloroform/methanol solubility and DCCD binding of the antigen were investigated. DCCD specifically inhibited the binding of anti-D IgG to Rh-positive red blood cells and to partially purified D antigen as determined by enzyme-linked immunoassays. The antigen was not only soluble in chloroform/methanol but was purified to apparent homogeneity by extraction with these solvents and subsequent discontinuous sucrose gradient centrifugation. The antigen's chloroform/methanol solubility, DCCD binding, low molecular weight, and previously reported phospholipid dependence allow classification of the D antigen as a proteolipid. The discovery that the D antigen is a proteolipid provides further clues to the antigen's cellular function.
D000937:Antigen-Antibody Reactions; D002234:Carbodiimides / Q000378:metabolism*; D002725:Chloroform; D004024:Dicyclohexylcarbodiimide / Q000378:metabolism*; D006801:Humans; D007074:Immunoglobulin G; D000432:Methanol; D011485:Protein Binding; D011510:Proteolipids / Q000097:blood*; D012204:Rh-Hr Blood-Group System / Q000032:analysis*; D012995:Solubility
D002234:Carbodiimides; D007074:Immunoglobulin G; D011510:Proteolipids; D012204:Rh-Hr Blood-Group System; D004024:Dicyclohexylcarbodiimide; D002725:Chloroform; D000432:Methanol