A 9-kDa protein component of VERY-LOW-DENSITY lipoproteins and chylomicron remnants. Apo C-III, synthesized in the liver, is an inhibitor of lipoprotein lipase. Apo C-III modulates the binding of chylomicron remnants and VLDL to receptors (receptors, ldl) thus decreases the uptake of triglyceride-rich particles by the liver cells and subsequent degradation. The normal Apo C-III is glycosylated. There are several polymorphic forms with varying amounts of SIALIC ACID (Apo C-III-0, Apo C-III-1, and Apo C-III-2).