Faculty Collaboration Database

The rate of internalization of the mannose 6-phosphate/insulin-like growth factor II receptor is enhanced by multivalent ligand binding. J Biol Chem 1999 Jan 08;274(2):1164-71

Date

01/05/1999

Pubmed ID

9873065

DOI

10.1074/jbc.274.2.1164

Scopus ID

2-s2.0-0033534489 (requires institutional sign-in at Scopus site)   93 Citations

Abstract

The cation-independent mannose 6-phosphate/insulin-like growth factor II receptor (M6P/IGF-II receptor) undergoes constitutive endocytosis, mediating the internalization of two unrelated classes of ligands, mannose 6-phosphate (Man-6-P)-containing acid hydrolases and insulin-like growth factor II (IGF-II). To determine the role of ligand valency in M6P/IGF-II receptor-mediated endocytosis, we measured the internalization rates of two ligands, beta-glucuronidase (a homotetramer bearing multiple Man-6-P moieties) and IGF-II. We found that beta-glucuronidase entered the cell approximately 3-4-fold faster than IGF-II. Unlabeled beta-glucuronidase stimulated the rate of internalization of 125I-IGF-II to equal that of 125I-beta-glucuronidase, but a bivalent synthetic tripeptide capable of occupying both Man-6-P-binding sites on the M6P/IGF-II receptor simultaneously did not. A mutant receptor with one of the two Man-6-P-binding sites inactivated retained the ability to internalize beta-glucuronidase faster than IGF-II. Thus, the increased rate of internalization required a multivalent ligand and a single Man-6-P-binding site on the receptor. M6P/IGF-II receptor solubilized and purified in Triton X-100 was present as a monomer, but association with beta-glucuronidase generated a complex composed of two receptors and one beta-glucuronidase. Neither IGF-II nor the synthetic peptide induced receptor dimerization. These results indicate that intermolecular cross-linking of the M6P/IGF-II receptor occurs upon binding of a multivalent ligand, resulting in an increased rate of internalization.

Author List

York SJ, Arneson LS, Gregory WT, Dahms NM, Kornfeld S

Author

Nancy M. Dahms PhD Professor in the Biochemistry department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Dimerization
Endocytosis
Glucuronidase
Humans
Insulin-Like Growth Factor II
Iodine Radioisotopes
Kinetics
Ligands
Protein Binding
Receptor, IGF Type 2
Receptors, Somatomedin
Recombinant Proteins