VIP Research Standard
Vasoactive intestinal peptide (CAS 37221-79-7) is a 28-residue peptide supplied as a 10 mg lyophilized powder in a 3 mL vial. It is an endogenous ligand at two class B GPCRs, VPAC1 and VPAC2, which it binds with comparable affinity but activates very differently — a dissociation that makes it a useful reference for receptor-subtype work.[1]
Mechanism of Action & Research Context
The molecular targets are VPAC1 and VPAC2, shared with pituitary adenylate cyclase activating polypeptide (PACAP), which additionally binds PAC1.[2]
Equal binding, unequal activation. VIP binds VPAC1-expressing HT-29 membranes and VPAC2-expressing Molt-4b membranes with near-identical high affinity (KD 1.6 ± 0.2 and 1.7 ± 0.9 nM). But functionally it is a potent VPAC1 agonist, driving a 200-fold cAMP increase, and only a weak VPAC2 agonist at 14-fold. Affinity and efficacy come apart here, which is exactly the kind of distinction a binding assay alone would miss.[1]
A natural fragment inverts the profile. VIP4-28, generated by human lymphocytes, binds both receptors with the same high affinity, acts as an even stronger VPAC1 agonist (400-fold cAMP increase), and is a potent VPAC2 antagonist — inhibiting VPAC2-mediated cAMP by up to 95% with no antagonism at VPAC1. Proteolytic processing of the parent peptide therefore produces a subtype-selective tool.[1]
Cell lines that express one receptor each. HT-29 (VPAC1 only) and Molt-4b (VPAC2 only) were identified by real-time RT-PCR, which is what makes clean subtype comparison possible.[1]
Downstream signalling extends beyond cAMP. The VIP/PACAP receptor cascades include transactivation of the epidermal growth factor receptor family, and the three receptor subtypes are overexpressed in several tissue types — which is why receptor distribution is measured alongside signalling.[2]
Research Applications
Primary fields of in vitro laboratory investigation include:
Receptor subtype binding and cAMP assays in single-subtype cell lines.[1]
Affinity-versus-efficacy dissociation studies, using VIP as the reference where the two diverge.[1]
Fragment and proteolysis work, comparing VIP against VIP4-28 and related fragments.[1]
Receptor expression profiling by real-time RT-PCR.[1,2]
Growth factor receptor transactivation studies.[2]
Analytical Documentation
Purity and identity vary by manufacturing lot. Kimera Chems does not publish a single fixed purity figure for this item; refer to the batch-specific Certificate of Analysis (COA) issued for the lot received, which reflects third-party analytical testing for that lot.
References
- Summers MA, O’Dorisio MS, Cox MO, Lara-Marquez M, Goetzl EJ. A lymphocyte-generated fragment of vasoactive intestinal peptide with VPAC1 agonist activity and VPAC2 antagonist effects. J Pharmacol Exp Ther. 2003;306(2):638–645. doi:10.1124/jpet.103.050583
- Moody TW, Nuche-Berenguer B, Jensen RT. Vasoactive intestinal peptide/pituitary adenylate cyclase activating polypeptide, and their receptors and cancer. Curr Opin Endocrinol Diabetes Obes. 2016;23(1):38–47. doi:10.1097/MED.0000000000000218
Storage & Handling
Store at controlled room temperature, sealed and protected from light.
Storage guidance is a house recommendation. Analytical documentation is per-lot release testing.
