Intracellular delivery of proteins into mammalian living cells by polyethylenimine-cationization

Junichiro Futami, Midori Kitazoe, Takashi Maeda, Emiko Nukui, Masakiyo Sakaguchi, Jun Kosaka, Masahiro Miyazaki, Megumi Kosaka, Hiroko Tada, Masaharu Seno, Junzo Sasaki, Nam Hu Huh, Masayoshi Namba, Hidenori Yamada

Research output: Contribution to journalArticlepeer-review

88 Citations (Scopus)


In the post-genomic era, there is pressing need for development of protein manipulation methodology to analyze functions of proteins in living cells. For this purpose, techniques to deliver functional proteins into living cells are currently being evaluated as alternative approaches to the introduction of transcriptionally active DNA. Here, we describe a novel method for efficient protein transduction into living cells in which a protein is simply cationized with polyethylenimine (PEI) by limited chemical conjugation. PEI-cationized proteins appear to adhere to the cell surface by ionic charge interaction and then internalize into cells in a receptor- and transporter-independent fashion. Since PEI is an organic macromolecule with a high cationic-charge density, limited coupling with PEI results in endowment of sufficient cationic charge to proteins without causing serious decline in their fundamental functions. A number of PEI-cationized proteins, such as ribonuclease (RNase), green fluorescent protein (GFP) and immunoglobulin (IgG), efficiently entered cells and functioned in the cytosol. Our results suggest that protein cationization techniques using PEI will be useful for the development of protein transduction technology.

Original languageEnglish
Pages (from-to)95-103
Number of pages9
JournalJournal of Bioscience and Bioengineering
Issue number2
Publication statusPublished - Feb 2005


  • Cationization
  • Chemical modification
  • Endocytosis
  • Polyethylenimine (PEI)
  • Protein transduction

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Applied Microbiology and Biotechnology


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