ApolipoproteinB Assay Kit (APOB)

Lipids are synthesised in the intestine or liver but must be transported to tissues and organs. However this is not possible without hydrophilic adaptation. Lipids are therefore transported by a series of micellar structures. These structures consist of an outer monolayer of protein (an apolipoprotein) and polar lipids (phospholipids and unesterified cholesterol) plus an inner core of neutral lipids (triglycerides and cholesterol esters). The apolipoproteins interact with a series of enzymes and tissue receptors and are therefore responsible for further metabolism and catabolism of the micelle. The B apolipoproteins are the main form of protein found in low density lipoproteins (LDL). Two forms of apo B are found in humans. The most common form is apo B-100 (or large B) which constitutes the apo B found in lipoproteins synthesised in the liver. The other form is apo B-48 (or small B), thought to be synthesised in the intestinal wall. Apo B is the main cholesterol carrying protein in the blood and is the ligand concerned with the uptake of cholesterol into cells by the LDL-receptor pathway. Apo B shows atherogenic signs and is thus useful for the evalution of coronary risk. Studies have shown that there is an inverse relationship between APOA-1 and coronary artery disease and a direct relationship with APO B such that pateints with CAD have generally reduced levels of APOA-1 and increased levels of APO B.