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sorLA (Sorting protein-related receptor) is a type-1 membrane protein of unknown function that is expressed in neurons. Its homology to sorting receptors that shuttle between the plasma membrane, endosomes, and the Golgi suggests a related function in neuronal trafficking processes. Because expression of sorLA is reduced in the brain of patients with(More)
We recently reported the isolation and sequencing of sortilin, a new putative sorting receptor that binds receptor-associated protein (RAP). The luminal N-terminus of sortilin comprises a consensus sequence for cleavage by furin, R41WRR44, which precedes a truncation originally found in sortilin isolated from human brain. We now show that the truncation(More)
Sortilin belongs to a growing family of multiligand type-1 receptors with homology to the yeast receptor Vps10p. Based on structural features and sortilin's intracellular predominance, we have proposed it to be a sorting receptor for ligands in the synthetic pathway as well as on the cell membrane. To test this hypothesis we examine here the cellular(More)
Steroid hormones are central regulators of a variety of biological processes. According to the free hormone hypothesis, steroids enter target cells by passive diffusion. However, recently we demonstrated that 25(OH) vitamin D(3) complexed to its plasma carrier, the vitamin D-binding protein, enters renal proximal tubules by receptor-mediated endocytosis.(More)
The 39-40-kDa receptor-associated protein (RAP) binds to the members of the low density lipoprotein receptor gene family and functions as a specialized endoplasmic reticulum/Golgi chaperone. Using RAP affinity chromatography, we have purified a novel approximately 250-kDa brain protein and isolated the corresponding cDNA. The gene, designated SORL1, maps to(More)
125I-insulin binding and receptor-mediated insulin degradation were studied in isolated human fat cells from subcutaneous tissue. A high albumin concentration during cell isolation and incubation protected the fragile human adipocyte from lysis. Binding of tracer was pH dependent with an optimum between 7.4 and 7.6. At 37 °C steady state was reached by 45(More)
Epithelial glycoprotein 330 (gp330) is structurally similar to the multifunctional alpha 2-macroglobulin receptor/low density lipoprotein receptor-related protein (alpha 2MR/LRP), gp330 and alpha 2MR/LRP bind Ca2+ with high affinity, and both receptors bind and mediate endocytosis of alpha 2MR-associated protein (RAP). In the present report, we describe(More)
The GPI-anchored urokinase plasminogen activator receptor (uPAR) does not internalize free urokinase (uPA). On the contrary, uPAR-bound complexes of uPA with its serpin inhibitors PAI-1 (plasminogen activator inhibitor type-1) or PN-1 (protease nexin-1) are readily internalized in several cell types. Here we address the question whether uPAR is internalized(More)