MECHANISMS OF CELLULAR UPTAKE OF THROMBIN-ANTITHROMBIN-II COMPLEXES -ROLE OF THE LOW-DENSITY-LIPOPROTEIN RECEPTOR-RELATED PROTEIN AS A SERPIN-ENZYME COMPLEX RECEPTOR

Serine proteinase inhibitors (serpins) such as antithrombin III inhibi t target proteinases by forming a stable complex with the enzyme. Once formed, several serpin-enzyme complexes (SECs) are removed from the c irculation by a receptor termed the SEC receptor that is present in th e liver. Until recently, the identity of this clearance receptor remai ned unknown; however, data are now available that strongly implicates one member of the low-density lipoprotein (LDL) receptor family as a c andidate for the SEC receptor. This receptor, known as the LDL recepto r-related protein (LRP), is a prominent liver receptor that is known t o bind numerous ligands that include proteinase-inhibitor complexes, m atrix proteins, and certain apolipoprotein E- and lipoprotein lipase-e nriched lipoproteins. (C) 1997, Elsevier Science Inc.