Human Kell Protein (KEL) Protein

Background

Kell (KEL), also known as Kell metallo-endopeptidase, is a membrane-bound glycoprotein found primarily on the surface of red blood cells (RBCs). It is a key player in the Kell blood group system, which is one of the most important blood group systems for transfusion medicine. The Kell blood group system includes various antigens, with the K (K1) and k (K2) antigens being the most clinically significant. These antigens are carried by the Kell protein, and variations in the expression of these antigens are associated with immune reactions in transfusion therapy and hemolytic disease of the newborn (HDN). Kell is also a metalloendopeptidase, which means it has enzymatic activity and is capable of cleaving peptide bonds in substrates, a function typical of certain metalloproteins. The Kell protein is involved in regulating the function and integrity of red blood cells, and it also plays a role in the interaction of the RBC with the immune system. Despite its primary association with blood group antigens, Kell is part of a larger group of proteins with endopeptidase activity. The protein is encoded by the KEL gene, located on the X chromosome (Xp21.1). This gene is expressed at high levels in erythroid precursor cells and mature erythrocytes, with its most significant role being the expression of the Kell antigens.