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Receptor activation and 2 distinct COOH- terminal motifs control G-CSF receptor distribution and internalization kinetics.

journal contribution
posted on 2004-01-15, 00:00 authored by L Aarts, O Roovers, Alister WardAlister Ward, I Touw
We have studied the intracellular distribution and internalization kinetics of the granulocyte colony-stimulating factor receptor (G-CSF-R) in living cells using fusion constructs of wild-type or mutant G-CSF-R and enhanced green fluorescent protein (EGFP). Under steady-state conditions the G-CSF-R localized predominantly to the Golgi apparatus, late endosomes, and lysosomes, with only low expression on the plasma membrane, resulting from spontaneous internalization. Internalization of the G-CSF-R was significantly accelerated by addition of G-CSF. This ligand-induced switch from slow to rapid internalization required the presence of G-CSF-R residue Trp650, previously shown to be essential for its signaling ability. Both spontaneous and ligand-induced internalization depended on 2 distinct amino acid stretches in the G-CSF-R COOH-terminus: 749-755, containing a dileucine internalization motif, and 756-769. Mutation of Ser749 at position –4 of the dileucine motif to Ala significantly reduced the rate of ligand-induced internalization. In contrast, mutation of Ser749 did not affect spontaneous G-CSF-R internalization, suggesting the involvement of a serine-threonine kinase specifically in ligand-accelerated internalization of the G-CSF-R. COOH-terminal truncation mutants of G-CSF-R, found in severe congenital neutropenia, lack the internalization motifs and were completely defective in both spontaneous and ligand-induced internalization. As a result, these mutants showed constitutively high cell-surface expression.

History

Journal

Blood

Volume

103

Issue

2

Pagination

571 - 579

Publisher

American Society of Hematology

Location

Washington, D.C.

ISSN

0006-4971

eISSN

1528-0020

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

2007, The American Society of Hematology