On the Protein Defect in Abetalipoproteinemia

Abstract

Abstract The plasma lipoproteins from a patient with abetalipoproteinemia were delipidated and fractionated; the lipid-free proteins (apoproteins) were compared by physical, chemical and immunological technics with the apoproteins from normal subjects. It was established that the major protein constituents of the very low-density lipoproteins, other than apoLP-ser, and the two predominant proteins of the high-density lipoproteins are present in plasma in abetalipoproteinemia and are identical to the corresponding apoproteins from normal subjects. As previously shown, low-density lipoprotein (LDL) and its principal protein component (or components), here designated apoLP-ser, were not detected by immunological tests. These findings indicate that the primary biochemical lesion in abetalipoproteinemia is a selective one affecting the main apoprotein (or proteins) of LDL.