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Biochem Biophys Res Commun. 1994 Nov 30;205(1):282-90.

Isolation and functional expression of human pancreatic peptidylglycine alpha-amidating monooxygenase.

Author information

1
First Department of Biochemistry, School of Medicine, Fukuoka University, Japan.

Erratum in

  • Biochem Biophys Res Commun 1995 Jan 17;206(2):805.

Abstract

Pancreastatin (PST) is processed from chromogranin A and the C-terminal amide of the peptide is an absolute requirement for biological activities. Human pancreatic carcinoma cells QGP-1 which produce both chromogranin A and PST were used to isolate cDNAs encoding two forms of peptidylglycine alpha-amidating monooxygenase (PAM). The two forms are a full length bifunctional enzyme and a variant lacking the transmembrane domain-coding region. When the cDNAs of these two forms were expressed in COS-7 cells, cells transfected with the predicted soluble form released into the culture medium a very much higher amidating activity which converts human chromogranin A-(273-302) to PST-29. The optimal pH for amidating activity was 5.4 and Cu2+, ascorbate and catalase were required as cofactors for the both forms of PAM. Km values for the membrane-bound and the soluble forms of PAM were 15.7 +/- 3.1 microM and 12.4 +/- 1.6 microM, respectively. These results demonstrate that both forms of PAM can function in the posttranslational processing of chromogranin A to PST in the environment of a secretory vesicle.

PMID:
7999037
DOI:
10.1006/bbrc.1994.2662
[Indexed for MEDLINE]

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