Signaling Peptide
Definition
A peptide whose function is to carry a message, binding a receptor to change what a cell does. Appetite, fluid balance and pituitary output are all regulated this way, by GLP-1, oxytocin and kisspeptin respectively.
Terms used in this definition
Other entries this definition refers to.
Where this term comes up
Entries whose definition mentions Signaling Peptide.
What this means for research sourcing
Foundational terminology for researchers new to peptide science. Volta's introductory resources connect these fundamentals to the compounds available for study.
Related Terms in Basics
D-Retro-Inverso
A design in which the sequence is read backwards and every L-amino acid is swapped for its D isomer. Side-chain geometry comes out close to the original while proteases, which recognise L-residues, no longer cut it. FOXO4-DRI is built this way.
Cyclization
Closing a peptide into a ring, head to tail or through a side-chain bridge. The ring has fewer conformations to lose and no free ends for exopeptidases to attack, which is why so many peptide drugs are cyclic.
PEGylation
Attaching polyethylene glycol chains to a peptide. The added hydrodynamic bulk slows glomerular filtration and shields the backbone from enzymes, so the molecule circulates for longer. PEG-MGF carries the name of the modification.
Acylation
Attaching a fatty acid chain so the molecule binds reversibly to serum albumin. The albumin-bound fraction acts as a circulating reservoir and clearance slows from hours to days. GLP-1 SM and cagrilintide both use it.
DAC (Drug Affinity Complex)
A maleimidopropionic acid linker that couples to albumin after administration. On CJC-1295 it takes the half-life from minutes to roughly eight days, which is the whole difference between the DAC and no-DAC versions of that compound.
Amino Acid
The unit a peptide is built from. Twenty of them are used to assemble human proteins, each carrying an amino group, a carboxyl group and a distinguishing side chain, and it is the side chains that decide how a finished peptide folds and what it binds.
Peptide
A chain of amino acids joined by peptide bonds, conventionally fewer than about 50 of them. The cut-off between a peptide and a protein is a convention rather than a chemical boundary, and several compounds supplied for research sit either side of it.
Protein
A long amino acid chain, usually above the 50-residue convention, that folds into a defined three-dimensional structure. Collagen, insulin and antibodies are proteins; the shorter chains studied as research peptides are not, although the chemistry of the backbone is identical.
