The low-density-lipoprotein receptor-related protein (LRP) is processed by furin in vivo and in vitro.
The low-density-lipoprotein receptor-related protein (LRP) is a multifunctional receptor involved in the clearance of a large number of diverse ligands, including proteases, protease-inhibitor complexes and lipoproteins. The mature receptor is composed of a 515 kDa and a 85 kDa subunit generated by proteolytic cleavage from a 600 kDa precursor polypeptide in a trans-Golgi compartment. Proteolytic processing occurs C-terminal to the tetrabasic amino acid sequence RHRR, a consensus recognition site for precursor processing endoproteases or convertases. In this study we have identified furin, a subtilisin-type protease, to be necessary for efficient processing of LRP in cells. Furin-deficient RPE.40 cells exhibited an impaired processing of endogenous LRP and of a recombinant soluble form of the receptor containing the processing site. The processing defect in RPE.40 cells could be complemented by expression of furin from a transfected cDNA in cultured cells and by purified furin in vitro. The impaired maturation of LRP in RPE.40 cells did not affect its intracellular transport, and correlated with a slight but consistent reduction in the endocytosis of LRP-specific ligands. These data suggest that proteolytic processing of LRP by furin is not necessary for intracellular trafficking but might be required for normal receptor activity.
Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas 75235, USA.
T E
TE
Willnow
J M
JM
Moehring
N M
NM
Inocencio
T J
TJ
Moehring
J
J
Herz
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D016466:CHO Cells / Q000378:metabolism; D006224:Cricetinae; D018076:DNA, Complementary / Q000235:genetics; D045683:Furin; D007457:Iodine Radioisotopes; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D051379:Mice; D008969:Molecular Sequence Data; D011499:Protein Processing, Post-Translational; D011971:Receptors, Immunologic / Q000378:metabolism*; D012680:Sensitivity and Specificity; D013381:Subtilisins / Q000235:genetics / Q000378:metabolism*; D010959:Tissue Plasminogen Activator / Q000493:pharmacokinetics; D014162:Transfection
D018076:DNA, Complementary; D007457:Iodine Radioisotopes; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D011971:Receptors, Immunologic; D013381:Subtilisins; D010959:Tissue Plasminogen Activator; D045683:Furin