title: Purification and sequencing of a rat intestinal 22 amino acid C-terminal CCK fragment.
abstract: Fractionation on Sephadex G50 gel of methanol extracts of rat intestine revealed two molecular forms of cholecystokinin (CCK) of about equal immunopotency: one form has an elution volume between CCK33 and CCK12; the other elutes in the salt region as does authentic CCK8. Purification and sequencing have demonstrated that the smaller molecular form is CCK8 with a sequence identical to the pork and sheep CCK8's that had previously been sequenced. Purification and sequencing of the larger molecular form reveals that it is a 22 amino acid C-terminal CCK fragment identical with pig CCK22 except that glycine instead of serine is present at the nineteenth residue from the C-terminus. This sequence is consistent with that predicted by cloned cDNA encoding preprocholecystokinin from a rat medullary thyroid carcinoma. CCK22 has not previously been reported to be a prominent molecular form in either pig or dog intestines.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002766:Cholecystokinin / Q000302:isolation & purification*; D007422:Intestines / Q000032:analysis*; D010446:Peptide Fragments / Q000302:isolation & purification*; D011499:Protein Processing, Post-Translational; D051381:Rats; D012844:Sincalide / Q000302:isolation & purification
chemical_list: D010446:Peptide Fragments; D002766:Cholecystokinin; C044926:cholecystokinin 22 C-terminal fragment; D012844:Sincalide