Prohormone convertase 1 (PC1) when expressed with pro cholecystokinin (pro CCK) in L cells performs three endoproteolytic cleavages which are observed in rat brain and in CCK-expressing endocrine cells in culture, including the production of glycine and arginine extended CCK8.
Pro CCK was expressed in an L cell line engineered to express PC1 and the products secreted into the media were characterized by a combination of RIA, gel filtration and HPLC. PC1 released from L cells, cleaved pro CCK generating the amino terminal pro peptide. PC1 also generated a peptide which after carboxypeptidase B treatment, was detected with an antiserum specific for CCK Gly. Neither of these peptides was found in media from L cells expressing pro CCK alone. This CCK Gly immunoreactive peptide was similar in size to CCK 8, and after treatment with arylsulfatase and carboxypeptidase B, it co-eluted on HPLC with unsulfated CCK 8 Gly. These results agree with previous studies which support a role for PC1 in generation of CCK 8. This is the first demonstration that PC1 acting alone is able to cleave pro CCK liberating the amino terminal pro peptide and a glycine and arginine extended CCK 8 which is the immediate precursor of CCK 8 amide.
Wang
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W
Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
Birch
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NP
Beinfeld
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MC
D000595:Amino Acid Sequence; D000818:Animals; D001120:Arginine / Q000378:metabolism; D016282:Aspartic Acid Endopeptidases / Q000096:biosynthesis / Q000378:metabolism*; D001921:Brain / Q000378:metabolism*; D043424:Carboxypeptidase B; D002268:Carboxypeptidases / Q000378:metabolism; D002766:Cholecystokinin / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D002850:Chromatography, Gel; D005998:Glycine / Q000378:metabolism; D007739:L Cells; D051379:Mice; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D045664:Proprotein Convertase 1; D043484:Proprotein Convertases; D011498:Protein Precursors / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D051381:Rats; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D012844:Sincalide / Q000737:chemistry / Q000378:metabolism*; D014162:Transfection
D010446:Peptide Fragments; D011498:Protein Precursors; D011994:Recombinant Proteins; C060249:procholecystokinin; D002766:Cholecystokinin; D001120:Arginine; D002268:Carboxypeptidases; D043424:Carboxypeptidase B; D043484:Proprotein Convertases; C473656:Pcsk1 protein, mouse; D045664:Proprotein Convertase 1; D016282:Aspartic Acid Endopeptidases; D012844:Sincalide; D005998:Glycine