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Updated: Oct 11, 2025

Construction of Cyclic Cell-Penetrating Peptides for Enhanced Penetration of Biological Barriers
Published on: September 19, 2022
The Coiled-Coil Forming Peptide (KVSALKE)5 Is a Cell Penetrating Peptide that Enhances the Intracellular Delivery of
Jie Li1, Jan Tuma2, Hesong Han1
1Department of Bioengineering, University of California, and the Innovative Genomics Institute, 2151 Berkeley Way, Berkeley, CA, 94720, USA.
Abstract:
Protein-based therapeutics have the potential to treat a variety of diseases, however, safe and effective methods for delivering them into cells need to be developed before their clinical potential can be realized. Peptide fusions have great potential for improving intracellular delivery of proteins. However, very few peptides have been identified that can increase the intracellular delivery of proteins, and new peptides that can enhance intracellular protein delivery are greatly needed. In this report, the authors demonstrate that the coiled-coil forming peptide (KVSALKE)5 (termed K5) can function as a cell penetrating peptide (CPP), and can also complex other proteins that contain its partner peptide E5. It is shown here that GFP and Cas9 fused to the K5 peptide has dramatically enhanced cell uptake in a variety of cell lines, and is able to edit neurons and astrocytes in the striatum and hippocampus of mice after a direct intracranial injection. Collectively, these studies demonstrate that the coiled-coil forming peptide (KVSALKE)5 is a new class of multifunctional CPPs that has great potential for improving the delivery of proteins into cells and in vivo.
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