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Updated: Apr 12, 2026

Direct Protein Delivery to Mammalian Cells Using Cell-permeable Cys2-His2 Zinc-finger Domains
Published on: March 25, 2015
Cationic PTD/CPP-mediated macromolecular delivery: charging into the cell.
Peter Lönn1,2, Steven F Dowdy1
1a 1 UCSD School of Medicine, Department of Cellular and Molecular Medicine , 9500 Gilman Dr., La Jolla, CA 92093-0686, USA sdowdy@ucsd.edu.
Protein transduction domains (PTDs), also known as cell-penetrating peptides (CPPs), are essential for delivering macromolecular therapeutics into cells. These peptides show great potential for treating diseases, with over 25 clinical trials underway.
Area of Science:
- Biotechnology
- Molecular Biology
- Drug Delivery
Background:
- Macromolecular therapeutics target intracellular pathways but require delivery vehicles.
- Protein transduction domains (PTDs), or cell-penetrating peptides (CPPs), facilitate cellular entry of macromolecules.
Purpose of the Study:
- To review the uptake and applications of arginine-rich PTDs/CPPs (TAT-PTD, Penetratin/Antp, 8R).
- To discuss the delivery of various cargos and modulation of cellular processes using PTDs/CPPs.
Main Methods:
- Review of endocytosis-mediated uptake mechanisms of PTDs/CPPs.
- Analysis of cell association, internalization, and endosomal escape.
- Examination of diverse cargos delivered and biological responses modulated.
Main Results:
- PTDs/CPPs demonstrate significant potential for delivering therapeutics into cells for research and in vivo studies.
- Over 25 clinical trials have utilized PTDs/CPPs, primarily the TAT-PTD.
Conclusions:
- PTDs/CPPs offer a promising strategy for macromolecular drug delivery.
- Challenges remain in achieving efficient endosomal escape and target-cell specificity.
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Published on: September 2, 2015
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