Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Query: EC:2.4.1.18 (
branching enzyme
)
628
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Misregulation of the E3 ubiquitin ligase
Parkin
and the kinase PINK1 underlie both inherited and idiopathic Parkinson's disease-associated neurodegeneration.
Parkin
and PINK1 work together to catalyze the assembly of ubiquitin chains on substrates located on the outer mitochondrial membrane to facilitate autophagic removal of damaged mitochondria through a process termed mitophagy. Quantitative measurements of
Parkin
-mediated chain assembly, both
in vitro
and on mitochondria, have revealed that chains are composed of Lys6, Lys11, Lys48, and Lys63 linkages. The combinatorial nature of these chains is further expanded by the ability of PINK1 to phosphorylate individual subunits. The precise architecture of chains produced by the coordinated action of PINK1 and
Parkin
, however, are unknown. Here, we demonstrate that quantitative middle-down mass spectrometry using uniformly
15
N-labeled ubiquitin variants as internal standards informs on the extent of chain branching. We find that
Parkin
is a prolific
branching enzyme
in vitro
. Quantitative middle-down mass spectrometry also reveals that phospho-Ser65-ubiquitin (pSer65-Ub)-a key activator of
Parkin
-is not incorporated into chains to a significant extent. Our results suggest that
Parkin
-mediated chain branching is "on-pathway", and branch points are the principal targets of the deubiquitinase USP30.
...
PMID:Quantitative Middle-Down MS Analysis of Parkin-Mediated Ubiquitin Chain Assembly. 3229 15
