TY - JOUR

T1 - A processing enzyme cleaving avian progastrin at post-Phe bonds

AU - Jensen, H

AU - Ørskov, C

AU - Rehfeld, J F

AU - Johnsen, A H

PY - 2001/5/5

Y1 - 2001/5/5

N2 - Neuroendocrine peptides mature partly through endoproteolytic processing of long precursor forms. Best characterised is cleavage at mono- and dibasic residues, but additional sites also exist. Among these is post-Phe cleavage, first suggested to participate in the processing of chicken progastrin. In order to characterise this new mechanism, antibodies recognising the processing products of post-Phe cleavage of chicken progastrin were produced for radioimmunoassay measurements and immunocytochemistry. High concentrations of the carboxyamidated C-terminus and the N-terminus of gastrin-53 were measured in extracts of the antrum. In addition, significant amounts were detected using an assay specific for the N-terminus of gastrin-30 and with another assay for the C-terminus of the corresponding peptide, gastrin-53(1-23), obtained after cleavage at the Phe(23)-Ala(24) bond of gastrin-53. Colocalisation in antral G-cells of the N-termini of gastrin-53 and gastrin-30 and of the C-terminus of gastrin-53(1-23) was confirmed by immunohistochemistry. Finally, we identified the intact N-terminal 1-23 fragment of gastrin-53 complementary to gastrin-30, verifying endoproteolytic cleavage at the Phe(23)-Ala(24) bond. Taken together, the results support the existence of vertebrate endoprotease cleaving hormone precursors at post-Phe sites.

AB - Neuroendocrine peptides mature partly through endoproteolytic processing of long precursor forms. Best characterised is cleavage at mono- and dibasic residues, but additional sites also exist. Among these is post-Phe cleavage, first suggested to participate in the processing of chicken progastrin. In order to characterise this new mechanism, antibodies recognising the processing products of post-Phe cleavage of chicken progastrin were produced for radioimmunoassay measurements and immunocytochemistry. High concentrations of the carboxyamidated C-terminus and the N-terminus of gastrin-53 were measured in extracts of the antrum. In addition, significant amounts were detected using an assay specific for the N-terminus of gastrin-30 and with another assay for the C-terminus of the corresponding peptide, gastrin-53(1-23), obtained after cleavage at the Phe(23)-Ala(24) bond of gastrin-53. Colocalisation in antral G-cells of the N-termini of gastrin-53 and gastrin-30 and of the C-terminus of gastrin-53(1-23) was confirmed by immunohistochemistry. Finally, we identified the intact N-terminal 1-23 fragment of gastrin-53 complementary to gastrin-30, verifying endoproteolytic cleavage at the Phe(23)-Ala(24) bond. Taken together, the results support the existence of vertebrate endoprotease cleaving hormone precursors at post-Phe sites.

KW - Amino Acid Sequence

KW - Animals

KW - Antibodies/immunology

KW - Binding Sites

KW - Chickens

KW - Chromatography, Gel

KW - Digestive System/metabolism

KW - Epitopes/immunology

KW - Fluorescent Antibody Technique

KW - Gastric Mucosa/metabolism

KW - Gastrins/chemistry

KW - Molecular Sequence Data

KW - Peptides/chemical synthesis

KW - Protein Precursors/chemistry

KW - Pyloric Antrum/metabolism

KW - Radioimmunoassay

KW - Tissue Extracts/chemistry

M3 - Journal article

C2 - 11343792

VL - 1547

SP - 64

EP - 71

JO - Biochimica et Biophysica Acta - Reviews on Cancer

JF - Biochimica et Biophysica Acta - Reviews on Cancer

SN - 0304-419X

IS - 1

ER -