Molecular Identification of a Novel Candidate Sorting Receptor Purified from Human Brain by Receptor-associated Protein Affinity Chromatography

doi:10.1074/jbc.272.6.3599

Molecular Identification of a Novel Candidate Sorting Receptor Purified from Human Brain by Receptor-associated Protein Affinity Chromatography*

From the^‡ Department of Medical Biochemistry, University of Aarhus, 8000 Aarhus C, Denmark and
^¶ The John F. Kennedy Institute, DK-2600 Glostrup, Denmark

^§ To whom correspondence should be addressed:
Dept. of Medical Biochemistry, University of Aarhus, Ole Worms Alle, Bldg. 170, DK-8000, Denmark
. Tel.: 45-89-422880; Fax: 45-86-131160.

Abstract

Receptor-associated protein (RAP) is an endoplasmic reticulum/Golgi protein involved in the processing of receptors of the low density lipoprotein receptor family. A ∼95-kDa membrane glycoprotein, designated gp95/sortilin, was purified from human brain extracts by RAP affinity chromatography and cloned in a human cDNA library. The gene maps to chromosome 1p and encodes an 833-amino acid type I receptor containing an N-terminal furin cleavage site immediately preceding the N terminus determined in the purified protein. Gp95/sortilin is expressed in several tissues including brain, spinal cord, and testis. Gp95/sortilin is not related to the low density lipoprotein receptor family but shows intriguing homologies to established sorting receptors: a 140-amino acid lumenal segment of sortilin representing a hitherto unrecognized type of extracellular module shows extensive homology to corresponding segments in each of the two lumenal domains of yeast Vps10p, and the extreme C terminus of the cytoplasmic tail of sortilin contains the casein kinase phosphorylation consensus site and an adjacent dileucine sorting motif that mediate assembly protein-1 binding and lysosomal sorting of the mannose-6-phosphate receptors. Expression of a chimeric receptor containing the cytoplasmic tail of gp95/sortilin demonstrates evidence that the tail conveys colocalization with the cation-independent mannose6-phosphate receptor in endosomes and the Golgi compartment.

Footnotes

↵* This work was supported by The Danish Medical Research Council, The Novo Nordisk Foundation, Danish Biotechnology Research and Development program 1995-1998, The Carlsberg Foundation, the Aage Bangs Foundation, and the Leo and Karen M. Nielsens Foundation. The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EMBL Data Bank with accession number(s) X98248[GenBank].
↵¹ The abbreviations used are:

M6P

mannose-6-phosphate

CD

cation-dependent

CHAPS

3-((cholamidopropyl)D-imethylammoniol)1-propanesulfonate

CI

cation-independent

LDL

low density lipoprotein

TGN

trans-Golgi network

Vps10p

vacuolar protein sorting 10 protein

PAGE

polyacrylamide gel electrophoresis

kb

kilobase(s)

aa

amino acid(s)

IL-2

interleukin 2.
- Received July 16, 1996.
- Revision received November 11, 1996.