HM1.24 is internalized from lipid rafts by Clathrin-mediated endocytosis through interaction with α-adaptin

Naoko Masuyama, Toshio Kuronita, Rika Tanaka, Tomonori Muto, Yuko Hirota, Azusa Takigawa, Hideaki Fujita, Yoshinori Aso, Jun Amano, Yoshitaka Tanaka

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121 Citations (Scopus)


HM1.24/Bst2/CD317 is a protein highly expressed in multiple myeloma cells and has unique topology with two membrane anchor domains, an NH2-terminal transmembrane domain and a glycosylphosphatidylinositol attached to the COOH terminus. We show here that human HM1.24 is localized not only on the cell surface but also in the trans-Golgi network and/or recycling endosomes, where it resides in detergent-resistant microdomains, lipid rafts. In contrast to other glycosylphosphatidylinositol-anchored proteins, HM1.24 was internalized from lipid rafts on the cell surface by clathrin-mediated endocytosis. Interestingly, a non-canonical tyrosine-based motif, which contains two tyrosine residues, Tyr-6 and Tyr-8, present in the NH2-terminal cytoplasmic tail, was essential for endocytosis through interaction with an α-adaptin, but not μ2-subunit, of the AP-2 complex. Indeed, an appendage domain of α-adaptin was identified as a protein interacting with the cytoplasmic tail of HM1.24. Furthermore, overexpression of the appendage domain of α-adaptin in cells depleted of α-adaptin could rescue the clathrin-mediated endocytosis of HM1.24 but not of the transferrin receptor. Taken together, our findings suggest that clathrin-dependent endocytosis of human HM1.24 from the cell surface lipid rafts is mediated by direct interaction with α-adaptin.

Original languageEnglish
Pages (from-to)15927-15941
Number of pages15
JournalJournal of Biological Chemistry
Issue number23
Publication statusPublished - Jun 5 2009

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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