Peptide research glossary
40 entries covering the receptors, pathways, mechanisms, and methodological terms used in peptide research. Each entry is short, citation-friendly, and cross-linked to the relevant peptide monographs and research stacks.
A
B
Bacteriostatic water
Sterile water containing 0.9% benzyl alcohol as a bacteriostatic preservative, the standard diluent for reconstituting lyophilised research peptides.
BDNF
Brain-Derived Neurotrophic Factor, a neurotrophin that supports neuronal survival, synaptic plasticity, and long-term potentiation in the central nervous system.
C
Cardiolipin
A unique dimeric phospholipid of the inner mitochondrial membrane that is essential for electron transport chain efficiency, cristae structure, and mitochondrial apoptotic signaling.
Cathelicidin family
A class of host-defence antimicrobial peptides derived from a conserved cathelin domain precursor, with LL-37 being the sole human member.
Collagen-I to Collagen-III ratio
The proportion of mature (type I) versus immature (type III) collagen in connective tissue, used as an index of scar maturation and tissue remodelling quality.
D
F
Fatty-acid conjugation
A chemical strategy that attaches a fatty-acid chain to a peptide drug, enabling reversible albumin binding that dramatically extends circulatory half-life for once-weekly dosing.
FPRL1 / FPR3
Formyl peptide receptor-like 1 (also called FPR3), a GPCR that functions as a primary receptor for the cytoprotective mitochondria-derived peptide Humanin.
G
G-actin sequestration
The binding and buffering of monomeric globular actin (G-actin) by sequestering proteins, regulating the cytoplasmic pool available for actin filament polymerization and cell motility.
Ghrelin receptor (GHSR-1a)
Growth hormone secretagogue receptor 1a, the primary receptor for the hunger hormone ghrelin, mediating GH release, appetite stimulation, and metabolic regulation.
GHRH receptor
Growth Hormone Releasing Hormone receptor expressed on pituitary somatotropes that triggers GH secretion when activated by endogenous GHRH or synthetic analogues.
GIP receptor
Glucose-dependent insulinotropic polypeptide receptor, an incretin GPCR on beta cells and adipocytes that enhances insulin secretion and modulates fat storage.
GLP-1 receptor
Glucagon-like peptide-1 receptor, a class B GPCR mediating incretin-driven insulin secretion, appetite suppression, and gastric emptying delay.
GnRH (Gonadotropin-Releasing Hormone)
A hypothalamic decapeptide released in pulses that drives pituitary LH and FSH secretion, governing the entire hypothalamic-pituitary-gonadal axis.
GPR54 / KISS1R
Kisspeptin receptor on hypothalamic GnRH neurons that gates the pulsatile release of GnRH and thereby controls the entire hypothalamic-pituitary-gonadal axis.
I
IGF-1 (Insulin-like Growth Factor 1)
A 70-amino-acid anabolic peptide hormone produced primarily by the liver in response to growth hormone signalling, mediating most of GH's growth-promoting effects.
Intranasal route
Administration of a peptide solution via nasal spray to achieve direct transport along olfactory and trigeminal nerve pathways into the CNS, bypassing the blood-brain barrier.
K
Khavinson bioregulator hypothesis
The theory that short tissue-specific peptides act as biological regulators by binding chromatin and restoring gene expression patterns that decline with age.
KNDy neurones
Hypothalamic arcuate nucleus neurones co-expressing kisspeptin, neurokinin B, and dynorphin that act as the central pulse generator for GnRH secretion.
L
Lyophilisation
A freeze-drying process that removes water from peptides under vacuum at low temperature, producing a stable powder that retains biological activity far longer than liquid formulations.
Lysyl oxidase
A copper-dependent amine oxidase that cross-links lysine and hydroxylysine residues in collagen and elastin, providing tensile strength and stability to connective tissue.
M
M2 macrophage polarisation
The pro-resolution, anti-inflammatory phenotype of macrophages that promotes tissue repair and dampens excessive immune responses.
MC1R
Melanocortin-1 receptor on melanocytes that controls eumelanin versus phaeomelanin production, determining skin and hair pigmentation in response to UV exposure.
MC4R (Melanocortin-4 receptor)
Melanocortin-4 receptor, a hypothalamic GPCR controlling energy balance, sexual function, and autonomic tone; the primary target of PT-141 for sexual arousal.
MHRA Special Authorisation (Specials)
A UK regulatory pathway that permits licensed pharmacies to import and supply unlicensed medicinal products for named patients when no suitable licensed alternative exists.
Mitochondrial unfolded protein response (UPRmt)
A mitochondria-to-nucleus stress signaling pathway that upregulates mitochondrial chaperones and proteases to restore proteostasis under organelle stress.
MMP-2 / MMP-9 (Matrix Metalloproteinases)
Zinc-dependent endopeptidases that degrade extracellular matrix components; key regulators of tissue remodelling, angiogenesis, and wound repair.
N
NF-κB
Nuclear factor kappa-light-chain-enhancer of activated B cells, the master transcription factor of inflammation that drives expression of cytokines, chemokines, and survival genes.
Nitric oxide (NO) system
A gasotransmitter signalling system in which eNOS, iNOS, and nNOS enzymes convert L-arginine to nitric oxide, regulating vascular tone, platelet aggregation, and tissue repair.
P
PepT1 transporter
A proton-dependent di/tripeptide transporter on intestinal epithelial cells that mediates oral absorption of small peptides and peptidomimetic drugs across the gut epithelium.
Pituitary somatotropes
GH-secreting acidophilic cells of the anterior pituitary that constitute 40–50% of its cell population and serve as the exclusive source of pulsatile growth hormone output.
Pulsatile dosing vs sustained signalling
The contrast between intermittent receptor stimulation mimicking physiological hormone pulses and continuous receptor activation, which often leads to receptor downregulation and signal attenuation.
S
STAT3
Signal Transducer and Activator of Transcription 3 — a transcription factor central to the JAK/STAT cascade and mitochondrial peptide signalling.
Subcutaneous (SC) administration
Injection of a substance into the subcutaneous fat layer beneath the skin, the standard route for most research peptide protocols due to slow, consistent systemic absorption.
T
Telomerase
An RNA-dependent DNA polymerase (reverse transcriptase) that extends telomeric DNA repeats at chromosome ends, counteracting replicative telomere shortening and cellular senescence.
TLR-9
Toll-like receptor 9 — an endosomal pattern recognition receptor on dendritic cells and B cells that detects unmethylated CpG DNA motifs to initiate innate immunity.
V
VEGF (Vascular Endothelial Growth Factor)
A family of secreted glycoproteins that drive angiogenesis, vasculogenesis, and vascular permeability by activating VEGF receptors on endothelial and progenitor cells.
VEGFR2
Vascular Endothelial Growth Factor Receptor 2, the primary signaling receptor mediating angiogenesis and endothelial cell survival downstream of VEGF.