Methods and compositions related to peptides and proteins with c-terminal elements

A. Example 1

Delivery of Nanoparticles, Drugs, and Other Substances into and Out of Cells

[0177]Phage display has been used to isolate a number of highly selective peptides for vascular targeting in vivo. Delivery of macromolecules and colloidal nanoparticles to cells is generally achieved by receptor targeting and / or using cell penetrating peptides.

[0178]1. Results

[0179]A panel of T7 bacteriophage-displayed peptide libraries was used to identify sequence motifs that lead to cellular uptake of the phage particles by PPC1 prostate carcinoma cells. T7 phage particles are composed of icosahedral nucleocapsid and tail fibers; displayed peptides are expressed as C-terminal fusions to major coat protein GP10, typically at density of 200-415 peptides / phage (FIG. 1A). Conventional T7 peptide libraries (random cyclic CX7C, and linear X7; X is a random residue) were used for the screening. New libraries were also designed to include an RXXR motif, which had been seen in other molecules, such as...

B. Example 2

C-End Rule

Neuropilin-1 Dependent Internalization of Peptides and Peptide-Coated Nanoparticles Exposing a C-Terminal Arginine

[0251]Cell type selective internalization of payloads is important for many biological processes and for targeted delivery of drugs and imaging agents. It has been established that cellular internalization and tissue penetration of nanoparticles can be achieved by C-terminally exposed R / KXXR / K (SEQ ID NO:23) peptide motif. This phenomenon is called the C-end Rule (CendR). Peptides containing R / KXXR / K (SEQ ID NO:23) motif in positions other than C-terminus are not internalized; however, uptake of such latent CendR peptides can be triggered by proteolytic cleavage. CendR peptides enter into cells by a mechanism that involves a critical component called neuropilin-1, which is a multi-ligand receptor known for its roles in vascular and nervous system patterning. The CendR technology can be applied to develop protease-activated delivery systems specific ...