Linked Life Data

9813057

Source:http://linkedlifedata.com/resource/pubmed/id/9813057

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
47
pubmed:dateCreated
1998-12-21
pubmed:abstractText
The platelet glycoprotein Ib-IX-V complex plays critical roles in adhering platelets to sites of blood vessel injury and in platelet aggregation under high fluid shear stress. The complex is composed of four membrane-spanning polypeptides: glycoprotein (GP) Ibalpha, GP Ibbeta, GP IX, and GP V. Glycoprotein Ibalpha contains a binding site for von Willebrand factor through which it mediates platelet adhesion; GP V is required for the complex to bind thrombin with high affinity; and both GP Ibbeta and GP IX are necessary for efficient plasma membrane expression of the complex. To further define the roles of the individual polypeptide subunits in the biosynthesis and intracellular transport of the GP Ib-IX-V complex, we studied full and partial complexes expressed in heterologous mammalian cells. We found that the full complex was formed within minutes in the endoplasmic reticulum before being transported into the Golgi cisternae. Approximately 160 min were required for the complex to be fully processed and to appear on the plasma membrane. About 25% of GP Ibalpha expressed as part of either a GP Ib-IX complex or a GP Ib-IX-V complex was degraded through a nonlysosomal pathway. Over 60% of GP Ibalpha, however, was degraded when it was expressed in partial complexes with only GP Ibbeta or GP IX. The increased degradation was blocked by treating cells either with brefeldin A to prevent the transport of proteins from the endoplasmic reticulum to the Golgi or with lysosomal inhibitors, indicating that GP Ibalpha expressed in partial complexes was targeted to the lysosomes for degradation. These results indicate that the presence of both GP Ibbeta and GP IX, but not the presence of GP V, is required for efficient processing and targeting of GP Ibalpha to the plasma membrane. Absence of either GP Ibbeta or GP IX increased the rate of GP Ibalpha degradation, providing an explanation for why mutation of their genes leads to deficient GP Ibalpha expression and platelet adhesion in Bernard-Soulier syndrome, the deficiency disorder of the complex.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
20
pubmed:volume
273
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
31449-54
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Synthesis, assembly, and intracellular transport of the platelet glycoprotein Ib-IX-V complex.
pubmed:affiliation
Division of Hematology/Oncology, Departments of Internal Medicine, Baylor College of Medicine and Veterans Affairs Medical Center, Houston, Texas 77030, USA. jfdong@bcm.tmc.edu
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't