Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.25.1 (proteasome)
 28,817 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Inactivating mutations of the gene encoding parkin are responsible for some forms of autosomal recessive juvenile Parkinson disease. Parkin is a ubiquitin ligase that ubiquitinates misfolded proteins targeted for the proteasome-dependent protein degradation pathway. Using the yeast two-hybrid system and co-immunoprecipitation methods, we identified synaptotagmin XI as a protein that interacts with parkin. Parkin binds to the C2A and C2B domains of synaptotagmin XI resulting in the polyubiquitination of synaptotagmin XI. Truncated and missense mutated parkins reduce parkin-sytXI binding affinity and ubiquitination. Parkin-mediated ubiquitination also enhances the turnover of sytXI. In sporadic PD brain sections, sytXI was found in the core of the Lewy bodies. Since synaptotagmin XI is a member of the synaptotagmin family that is well characterized in their importance for vesicle formation and docking, the interaction with this protein suggests a role for parkin in the regulation of the synaptic vesicle pool and in vesicle release. Loss of parkin could thus affect multiple proteins controlling vesicle pools, docking and release and explain the deficits in dopaminergic function seen in patients with parkin mutations.
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PMID:The autosomal recessive juvenile Parkinson disease gene product, parkin, interacts with and ubiquitinates synaptotagmin XI. 1292 69

Parkinson's disease (PD) is characterized by selective degeneration of neurons in the substantia nigra and subsequent dysfunction of dopaminergic neurotransmission. Genes identified in familial forms of PD encode proteins that are linked to the ubiquitin-proteasome system indicating the pathogenic relevance of disturbed protein degradation in PD. Some of them, i.e. alpha-synuclein, parkin and synphilin-1, have been implicated in presynaptic neurotransmission based on their localization in synaptic vesicles. Synaptotagmin XI is linked to the pathogenesis of PD based on its identification as a substrate of the ubiquitin-E3-ligase parkin. Moreover synaptotagmin XI is involved in the maintainance of synaptic function and represents a component of Lewy bodies (LB) in brains of PD patients. Therefore, we performed a detailed mutation analysis of the synaptotagmin XI gene in a large sample of 393 familial and sporadic PD patients. We did not find any disease causing mutations arguing against a major role of mutations in the synaptotagmin XI gene in the pathogenesis of PD.
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PMID:Screening for mutations in synaptotagmin XI in Parkinson's disease. 1535 86