Pepducins are novel cell-penetrating peptides that act as intracellular

Intracellular

Not to be confused with intercellular, meaning "between cells".In cell biology, molecular biology and related fields, the word intracellular means "inside the cell".It is used in contrast to extracellular...

 modulators of signal transference from receptors to G protein

G protein

G proteins are a family of proteins involved in transmitting chemical signals outside the cell, and causing changes inside the cell. They communicate signals from many hormones, neurotransmitters, and other signaling factors. G protein-coupled receptors are transmembrane receptors...

s. Pepducins were first developed at the Tufts Medical Center

Tufts Medical Center

Tufts Medical Center is a medical institution in Boston, Massachusetts occupying space between Chinatown and the Theater District....

 laboratories of Dr. Athan Kuliopulos and Dr. Lidija Covic .

Pepducins utilize lipidated fragments of intracellular G protein-coupled receptor

G protein-coupled receptor

G protein-coupled receptors , also known as seven-transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptor, and G protein-linked receptors , comprise a large protein family of transmembrane receptors that sense molecules outside the cell and activate inside signal...

 loops to modulate GPCR action in targeted cell-signaling pathways

Cell signaling

Cell signaling is part of a complex system of communication that governs basic cellular activities and coordinates cell actions. The ability of cells to perceive and correctly respond to their microenvironment is the basis of development, tissue repair, and immunity as well as normal tissue...

 . A Pepducin molecule

Molecule

A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...

 comprises a short peptide derived from a GPCR intracellular loop tethered to a hydrophobic moiety. This structure allows Pepducin lipopeptides  to anchor in the cell membrane

Cell membrane

The cell membrane or plasma membrane is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. It basically protects the cell...

 lipid bilayer

Lipid bilayer

The lipid bilayer is a thin membrane made of two layers of lipid molecules. These membranes are flat sheets that form a continuous barrier around cells. The cell membrane of almost all living organisms and many viruses are made of a lipid bilayer, as are the membranes surrounding the cell nucleus...

 and target the GPCR/G protein interface via a unique intracellular allosteric  mechanism. Pepducins for over 15 different GPCRs have been successfully produced, several of which have shown activity in preclinical in vivo

In vivo

In vivo is experimentation using a whole, living organism as opposed to a partial or dead organism, or an in vitro controlled environment. Animal testing and clinical trials are two forms of in vivo research...

models.

An anti-PAR4 pepducin extended bleeding time in mice and protected against systemic platelet activation and thrombosis.

A CXCR4

CXCR4

C-X-C chemokine receptor type 4 also known as fusin or CD184 is a protein that in humans is encoded by the CXCR4 gene.- Function :...

 agonist

Agonist

An agonist is a chemical that binds to a receptor of a cell and triggers a response by that cell. Agonists often mimic the action of a naturally occurring substance...

pepducin mobilizes bone marrow hematopoietic cells.

As of 2011 none have entered clinical trials, although progress continues to be made.