Processing of procarboxypeptidase E into carboxypeptidase E occurs in secretory vesicles

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

Carboxypeptidase E (CPE) functions in the posttranslational processing of bioactive peptides. Like other peptide processing enzymes, CPE is initially produced as a precursor ('proCPE') that undergoes posttranslational processing at a site containing five adjacent Arg residues near the N- terminus and at other sites near the C-terminus of proCPE. The time course of the N-terminal processing step suggests that this conversion occurs in either the Golgi apparatus or the secretory vesicles. To delineate further the site of proCPE processing, pulse/chase analysis was performed under conditions that block transit out of the Golgi apparatus (brefeldin A, carbonyl cyanide m-chlorophenylhydrazone, or 20°C) or that block acidification of vesicles (chloroquine, monensin, or ammonium chloride). The results of these analysis suggest that efficient proCPE processing requires an acidic post-Golgi compartment. To test whether known processing enzymes can perform this cleavage, purified proCPE was incubated with furin, prohormone convertase 1, or a dynorphin converting enzyme, and the products were analyzed on denaturing polyacrylamide gels. Furin cleaves proCPE within the N-terminal region, although the reaction is not very efficient, requiring relatively large amounts of furin or long incubation times. The other two peptide processing enzymes did not cleave proCPE, whereas a relatively small amount of secretory granule extract was able to convert proCPE into CPE. Taken together, these findings suggest that the conversion of proCPE into CPE occurs primarily in secretory vesicles.

Original languageEnglish (US)
Pages (from-to)444-453
Number of pages10
JournalJournal of Neurochemistry
Volume65
Issue number1
StatePublished - 1995

Fingerprint

Carboxypeptidase H
Secretory Vesicles
Furin
Golgi Apparatus
Processing
Peptides
Proprotein Convertase 1
Enzymes
Brefeldin A
Monensin
Ammonium Chloride
Chloroquine
procarboxypeptidase E
Acidification

Keywords

  • Carboxy-peptidase H
  • Carboxypeptidase E
  • Enkephalin convertase
  • Peptide processing
  • Prohormone convertase

ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience

Cite this

Processing of procarboxypeptidase E into carboxypeptidase E occurs in secretory vesicles. / Song, L.; Fricker, Lloyd D.

In: Journal of Neurochemistry, Vol. 65, No. 1, 1995, p. 444-453.

Research output: Contribution to journalArticle

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