Hormone · Procholecystokinin-derived peptide hormone
Cholecystokinin (CCK-33)
Also known as CCK-33
A 33-residue processed CCK peptide for studying sulphation-dependent receptor recognition and digestive tissue signalling.
- Length
- 33 amino acids
- Half-life
- Not well characterised
- Mechanism
- Amidated CCK-33 activates CCK1 and CCK2 receptors, principally engaging Gq/11-dependent phospholipase C signalling and calcium mobilisation. Sulphation of the tyrosine seven residues from the C-terminus strongly favours high-affinity CCK1 recognition, while CCK2 recognition is less sulphation-dependent.
- Studied in
- Pancreatic acinar preparations, isolated smooth muscle and recombinant receptor systems use CCK-33 to study secretion, contractile signalling and ligand recognition.
About Cholecystokinin (CCK-33)
Cholecystokinin (CCK-33) is a 33-residue product of procholecystokinin processing and was a central peptide in early biochemical characterisation of intestinal CCK. It contains the conserved amidated C-terminal sequence shared by receptor-active CCK forms, with an N-terminal extension beyond CCK-8. Native preparations can include sulphated and non-sulphated species. The exact species sequence, terminal chemistry and sulphation state must therefore be specified rather than inferred from the name CCK-33 alone.
The two principal CCK receptors discriminate structural features differently. CCK1 recognition strongly depends on the sulphated tyrosine within the C-terminal region, whereas CCK2 receptors also recognise gastrin and tolerate unsulphated CCK ligands more readily. Laboratory comparisons of CCK-33 with shorter fragments examine how peptide length influences receptor interaction, degradation and tissue responses. Pancreatic acinar cells, smooth-muscle preparations and receptor-transfected cells provide complementary readouts of secretion, contraction and intracellular signalling under controlled experimental conditions.
Laboratory notes
- Record species sequence, sulphation state and C-terminal amidation for every batch; these are essential identifiers for cross-study comparisons.
- Use analytical methods validated for sulphated peptides, since sulphate loss during mass spectrometric analysis can complicate identity assignment.
- Measure peptide stability in the actual assay medium, particularly when using enzyme-rich tissue preparations.
Storage and reconstitution basics: storage guide.
Questions about Cholecystokinin (CCK-33)
Does the name CCK-33 specify whether the peptide is sulphated?
No. The name specifies chain length, not sulphation state. Check the sequence annotation and analytical documentation.
What distinguishes CCK-33 from CCK-8?
CCK-33 has a 25-residue N-terminal extension relative to the corresponding CCK-8 sequence. They share the receptor-active C-terminal region but can differ in degradation and assay behaviour.
Which assays can separate CCK1 from CCK2 activity?
Use separately expressed receptor subtypes, subtype-selective antagonist controls and matched signalling readouts. A tissue response alone may not establish receptor identity.
Is Cholecystokinin (CCK-33) 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.