Cholecystokinin (CCK) is a peptide studied in laboratory research as a tool compound for the cholecystokinin receptors CCK1 (CCK-A) and CCK2 (CCK-B), both class A G protein-coupled receptors, in vitro. Endogenous CCK occurs in several molecular forms of different lengths — including CCK-58, CCK-33, and CCK-8 — that share a conserved C-terminal sequence, and laboratory work uses defined synthetic forms so that receptor experiments are reproducible from lot to lot.

Structure: the biologically studied C-terminal octapeptide CCK-8 has the sequence Asp-Tyr(SO3H)-Met-Gly-Trp-Met-Asp-Phe-NH2. The sulfated tyrosine (Tyr7 sulfation state) is a key structural variable in laboratory studies because sulfated and unsulfated forms show different binding behavior at CCK1 versus CCK2 in vitro, which makes the sulfation state an important identity attribute on the certificate of analysis. Identity and purity of research material are confirmed by HPLC and mass spectrometry, and the lot-matched COA is reviewed before use.

Laboratory applications: cell culture and receptor-binding assays probing CCK receptor signaling (calcium mobilization and inositol phosphate readouts), structure-activity studies comparing CCK forms and fragments, and use as a reference agonist alongside selective antagonist controls in receptor pharmacology experiments. Vehicle controls, analytical verification, and replication are standard. In vitro findings describe receptor behavior in laboratory systems only; no conclusions about human use can be drawn from them.

Analytical notes: store lyophilized material sealed, protected from light and moisture; verify identity and purity by HPLC/MS on receipt; avoid repeated freeze-thaw cycles; record lot numbers in laboratory documentation.

Disclaimer: This material is supplied for laboratory research purposes only. Not for human consumption. Not for medical, therapeutic, diagnostic, or veterinary use. No dosing, reconstitution-for-use, or efficacy information is provided or implied.

Citations: Rehfeld JF, cholecystokinin molecular forms reviews; Dufresne M et al., Cholecystokinin and Gastrin Receptors, Physiological Reviews (2006); standard HPLC/MS peptide characterization methods.