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.
Willnow
T E
TE
Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas 75235, USA.
Moehring
J M
JM
Inocencio
N M
NM
Moehring
T J
TJ
Herz
J
J
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