Tirzepatide - Frequently Asked Questions

The entry classifies it as a unimolecular dual GIP and GLP-1 receptor agonist - a synthetic 39-residue acylated peptide. 'Unimolecular dual agonist' means a single molecule activates two different receptors: the GIP receptor (GIPR) and the GLP-1 receptor (GLP-1R), both of which are class-B secretin-family G-protein-coupled receptors. It is studied as the reference dual-incretin agonist for receptor-signaling and structure-activity work.

It activates two class-B GPCRs, GIPR and GLP-1R. In recombinant-cell assays it engages each receptor's Gs-coupling pathway, activating adenylyl cyclase and raising intracellular cyclic AMP (cAMP). Because both receptors converge on the same Gs/adenylyl-cyclase/cAMP second-messenger route, the two receptors are typically studied in separate single-receptor cell lines so each potency can be measured independently.

The entry reports a GIPR EC50 of approximately 0.042 nM and a GLP-1R EC50 of approximately 0.086 nM, attributed to Coskun et al. 2018 and Selleck. These are cAMP-accumulation EC50 values (half-maximal effective concentrations). Both are sub-nanomolar, and the roughly two-fold difference indicates marginally higher potency at GIPR than at GLP-1R in these assays.

Aib (alpha-aminoisobutyric acid) is a non-natural residue. According to the entry, the Aib substitutions at positions 2 and 13 confer resistance to dipeptidyl-peptidase-IV (DPP-IV) cleavage - the protease that degrades native incretins at the N-terminus. This engineered resistance helps the intact, signaling-competent molecule persist in protease-containing conditions.

The C20 fatty-diacid moiety drives reversible albumin binding, which the entry states extends plasma residence. This is a lipidation-based persistence mechanism: the acyl chain transiently associates with serum albumin, lengthening the molecule's effective lifetime in plasma-containing systems. It is also relevant at the bench because albumin in assay media can reduce free-peptide availability.

The molecular weight is 4813.5 g/mol and the molecular formula is C225H348N48O68 (attributed to Selleck Chemicals). The molecular weight is the key conversion constant for turning a supplied peptide mass into a molar concentration when preparing assay stocks. The formula contains no sulfur, indicating no cysteine-derived disulfide bridging is implied by the composition data.

The CAS registry number is 2023788-19-2. This unique chemical identifier links the exact molecular entity to procurement and recordkeeping, letting an investigator confirm that material used in an assay matches the molecule described in the source set.

It means the 39-residue scaffold is derived from the native glucose-dependent insulinotropic polypeptide (GIP) sequence rather than from GLP-1, even though the engineered molecule activates both GIPR and GLP-1R. The entry describes it as engineered on the native GIP backbone, with the full sequence reported per Coskun et al. 2018.

Three: dual GIPR/GLP-1R cAMP-signaling potency assays; incretin-receptor structure-activity and DPP-IV-resistance studies; and albumin-binding pharmacokinetic-extension research. Each maps onto specific data in the entry - the potency EC50 values, the Aib/backbone design, and the C20 acyl albumin-binding feature, respectively.

Reconstitution is a laboratory-handling procedure. The supplied peptide mass is divided by the volume of bacteriostatic water added to give a mass-per-volume concentration, which is then divided by the molecular weight 4813.5 g/mol to express the stock in molar units. Working concentrations in the reported sub-nanomolar-to-nanomolar range are reached by serial dilution. This describes bench preparation only, not any dosing protocol.

No numeric half-life is provided. The entry describes structural persistence mechanisms - DPP-IV resistance from the position-2 and position-13 Aib substitutions and extended plasma residence from C20-fatty-diacid-mediated reversible albumin binding - but gives no measured elimination half-life or clearance constant. General lyophilized-peptide storage principles fill the gap and are flagged as general, not peptide-specific.

The primary citation is Coskun, T., et al. (2018), 'LY3298176, a novel dual GIP and GLP-1 receptor agonist for the treatment of type 2 diabetes mellitus: From discovery to clinical proof of concept,' in Molecular Metabolism (DOI 10.1016/j.molmet.2018.09.009, PMID 30473097). Physicochemical reference values are additionally attributed to Selleck Chemicals.