Activation of a membrane-bound serine protease matriptase on the cell surface.
J Biochem
; 146(2): 273-82, 2009 Aug.
Article
in En
| MEDLINE
| ID: mdl-19398443
ABSTRACT
Matriptase is a type II transmembrane serine protease. The activation (i.e. conversion of the single-chain pro-form to the disulphide-linked-two-chain active form) of this enzyme is known to occur via a mechanism requiring its catalytic triad. We reported previously that the activated enzyme was produced in the conditioned medium when full-length rat matriptase was expressed in monkey kidney COS-1 cells. The present study aimed to address when and where the matriptase activation occurs. COS-1 cells expressing matriptase were labelled with a membrane-impermeable biotin derivative and then solubilized with Triton. Both activated and non-activated matriptase molecules were detected in the avidin precipitants of Triton extracts, whereas only the non-activated molecules were detected in the flow-through fraction of avidin-precipitation procedure. Single-chain matriptase has been thought to have an inherent activity. Indeed, a secreted single-chain variant of recombinant matriptase bearing mutation at the activation-cleavage site was found to exhibit the activity in hydrolyzing a synthetic peptide substrate at pH 7.5. However, the variant had little activity at pH 5.5, as found in the lumen of post-Golgi secretory vesicles. Altogether, it is concluded that the activation of matriptase may occur when the enzyme reaches the cell surface.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Serine Endopeptidases
/
Cell Membrane
Limits:
Animals
Language:
En
Journal:
J Biochem
Year:
2009
Document type:
Article
Affiliation country:
Japón