The Microtubule-binding Protein Hook3 Interacts with a Cytoplasmic Domain of Scavenger Receptor A
| Autor: | Yoshio Kuroki, Takeyuki Shimizu, Hiroaki Mitsuzawa, Chiaki Nishitani, Helmut Krämer, Hitomi Sano, Masaho Ishino |
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| Rok vydání: | 2007 |
| Předmět: |
Cytoplasm
Small interfering RNA Biology Ligands Models Biological Biochemistry Cell Line Mice Two-Hybrid System Techniques Enzyme-linked receptor Animals Humans Protein Isoforms 5-HT5A receptor RNA Small Interfering Scavenger receptor Cell adhesion Receptor Molecular Biology Binding protein Scavenger Receptors Class A Cell Biology Ligand (biochemistry) Protein Structure Tertiary Rats Microtubule-Associated Proteins Protein Binding |
| Zdroj: | Journal of Biological Chemistry. 282:7973-7981 |
| ISSN: | 0021-9258 |
| DOI: | 10.1074/jbc.m611537200 |
| Popis: | The class A scavenger receptor (SR-A) is a multifunctional transmembrane glycoprotein that is implicated in atherogenesis, innate immunity, and cell adhesion. Despite extensive structure-function studies of the receptor, intracellular molecules that directly interact with SR-A and regulate the receptor trafficking have not been determined. In the current study, we have identified a microtubule-binding protein, Hook3, as a novel interacting partner of SR-A. The association between a rat Hook3 isoform and SR-A was suggested by yeast two-hybrid screening and mass spectrometry analysis of SR-A-cytoplasmic domain-bound proteins in rat alveolar macrophages. The binding of overexpressed and endogenous human Hook3 to SR-A was demonstrated by pull-down assay and co-immunoprecipitations. Furthermore, endogenous murine SR-A and HK3 co-sedimented from cell lysates isolated from Raw264.7 murine macrophage cells. The interaction of Hook3 with SR-A was significantly stimulated after SR-A had recognized the extracellular ligand. Studies using truncations demonstrated that the positively charged C-terminal Val614-Ala717 region of human Hook3 was required for the interaction with the negatively charged residues, Glu12, Asp13, and Asp15 in the human SR-A cytoplasmic domain. By transfecting small interfering RNA targeting Hook3, total and surface expression, receptor-mediated ligand uptake and protein stability of SR-A were significantly promoted, whereas the protein synthesis and maturation were not altered. We propose for the first time that Hook3 may participate in the turnover of the endocytosed scavenger receptor. |
| Databáze: | OpenAIRE |
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