In:
Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 100, No. 16 ( 2003-08-05), p. 9590-9595
Abstract:
Multistep proteolytic mechanisms are essential for converting proprotein
precursors into active peptide neurotransmitters and hormones. Cysteine proteases have been implicated in the processing of proenkephalin and other
neuropeptide precursors. Although the papain family of cysteine proteases has been considered the primary proteases of the lysosomal degradation pathway,
more recent studies indicate that functions of these enzymes are linked to specific biological processes. However, few protein substrates have been
d escribed for members of this family. We show here that secretory vesicle
cathepsin L is the responsible cysteine protease of chromaffin granules for converting proenkephalin to the active enkephalin peptide neurotransmitter.
The cysteine protease activity was identified as cathepsin L by affinity labeling with an activity-based probe for cysteine proteases followed by mass
spectrometry for peptide sequencing. Production of [Met] enkephalin by
cathepsin L occurred by proteolytic processing at dibasic and monobasic prohormone-processing sites. Cellular studies showed the colocalization of
cathepsin L with [Met] enkephalin in secretory vesicles of neuroendocrine
chromaffin cells by immunofluorescent confocal and immunoelectron microscopy. Functional localization of cathepsin L to the regulated secretory pathway was
demonstrated by its cosecretion with [Met] enkephalin. Finally, in cathepsin L
gene knockout mice, [Met] enkephalin levels in brain were reduced
significantly; this occurred with an increase in the relative amounts of enkephalin precursor. These findings indicate a previously uncharacterized
biological role for secretory vesicle cathepsin L in the production of [Met]enkephalin, an endogenous peptide neurotransmitter.
Type of Medium:
Online Resource
ISSN:
0027-8424
,
1091-6490
DOI:
10.1073/pnas.1531542100
Language:
English
Publisher:
Proceedings of the National Academy of Sciences
Publication Date:
2003
detail.hit.zdb_id:
209104-5
detail.hit.zdb_id:
1461794-8
SSG:
11
SSG:
12
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