Linked Life Data

14623250

Source:http://linkedlifedata.com/resource/pubmed/id/14623250

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2003-11-18
pubmed:abstractText
The ubiquitin-proteasome system is essential for intracellular protein degradation, but there are few studies of this system in the extracellular milieu. Recently, we reported that a 70-kDa sperm receptor, HrVC70, on the vitelline coat is ubiquitinated and then degraded by the sperm proteasome during fertilization of the ascidian, Halocynthia roretzi. Here, we investigated the mechanism of extracellular ubiquitination. The HrVC70-ubiquitinating enzyme activity was found to be released from the activated sperm during the fertilization process. This enzyme was purified from an activated sperm exudate, by chromatography on DEAE-cellulose and ubiquitin-agarose columns, and by glycerol density gradient centrifugation. The molecular mass of the enzyme was estimated to be 700 kDa. The purified enzyme requires CaCl2 and MgATP for activity, and is active in seawater. The purified enzyme preparation, but not the crude enzyme preparation, showed narrow substrate specificity to HrVC70. Moreover, ATP and ubiquitin are released from the activated sperm to the surrounding seawater during fertilization. These results indicate that ascidian sperm release a novel extracellular ubiquitinating enzyme system together with ATP and ubiquitin during penetration of the vitelline coat of the egg, which catalyzes the ubiquitination of the HrVC70, an essential component of ascidian fertilization.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0012-1606
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
264
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
299-307
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2003
pubmed:articleTitle
Extracellular ubiquitin system implicated in fertilization of the ascidian, Halocynthia roretzi: isolation and characterization.
pubmed:affiliation
Department of Biochemistry, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't