Cholecystokinin (CCK-4)

Also known as CCK-4; CCK tetrapeptide

The amidated C-terminal CCK tetrapeptide, used as a compact probe of CCK2 receptor signalling.

Length: 4 amino acids
Half-life: Not well characterised
Mechanism: CCK-4 activates CCK2 receptors, also known as CCK-B or gastrin receptors, which principally signal through Gq/11, phospholipase C and intracellular calcium mobilisation. It has much weaker activity at CCK1 receptors than longer, appropriately sulphated CCK peptides.
Studied in: Receptor-expressing cell lines, neural tissue preparations and animal neurobiology models use CCK-4 to investigate CCK2-dependent signalling.

About Cholecystokinin (CCK-4)

Cholecystokinin (CCK-4) is the amidated tetrapeptide Trp-Met-Asp-Phe-NH2, corresponding to the shared C-terminal sequence of cholecystokinin and gastrin. Structure–activity studies identified this region as a minimal receptor-active motif within the family. Unlike longer CCK peptides, CCK-4 contains no tyrosine and therefore cannot carry the tyrosine sulphate group associated with strong CCK1 receptor recognition. Its small size makes it a useful comparator for experiments examining peptide length and receptor discrimination.

CCK2 receptors recognise the shared amidated C-terminal motif of gastrin and CCK, whereas CCK1 receptors have more extensive structural requirements. In recombinant systems, CCK-4 can be studied through calcium mobilisation, inositol phosphate accumulation and competitive binding. Neural preparations provide additional contexts for examining receptor-dependent changes in cellular activity. Results require attention to receptor density and peptide degradation, since these variables can change apparent potency without changing the peptide's primary sequence.

Laboratory notes

Monitor methionine oxidation during storage and assay preparation; an oxidised species may have altered chromatographic and functional properties.
Verify the WMDF-NH2 sequence and terminal amidation against the certificate of analysis.
Include receptor-negative cells and a validated CCK2 antagonist when interpreting calcium responses.

Storage and reconstitution basics: storage guide.

Questions about Cholecystokinin (CCK-4)

Can CCK-4 be supplied as a tyrosine-sulphated peptide?

The native CCK-4 sequence contains no tyrosine. Tyrosine sulphation applies to longer CCK forms, not to this tetrapeptide.

Why is CCK-4 associated mainly with CCK2 assays?

CCK2 receptors recognise the shared C-terminal tetrapeptide motif, while high-affinity CCK1 recognition generally requires additional CCK residues and the correctly positioned sulphated tyrosine.

Does CCK-4 distinguish CCK signalling from gastrin signalling?

No. CCK and gastrin share this terminal motif and both can activate CCK2 receptors. CCK-4 probes receptor activity rather than the biological source of an endogenous ligand.

Is Cholecystokinin (CCK-4) for human use?

No. It is supplied strictly for in-vitro laboratory research and is not for human or animal consumption.

Related research peptides

All products are sold for laboratory research use only. Not for human consumption, not a medicine, not for diagnosing, treating or preventing any condition.