Linked Life Data

7019224

Source:http://linkedlifedata.com/resource/pubmed/id/7019224

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1981-9-15
pubmed:abstractText
In the studies reported here, we investigated whether the degradation of the acetylcholine receptor (AChR) in cultured muscle cells involves similar mechanisms as, and is controlled in a manner similar to, the catabolism of the bulk of cell protein. We compared these processes after labeling cell protein with radioactive leucine or phenylalanine for 24 hours, or labeling the acetylcholine receptor with (125I)-bungarotoxin. The apparent average half-life of cell protein was 38 +/- 2 hours and that of the receptor-toxin complex was 25 +/- 1 hours. Incubation in media lacking serum and embryo extract accelerated the degradation of both average protein and the receptor-toxin complex. Insulin reduced the rate of catabolism of both average protein and the receptor-toxin complex toward levels seen in the presence of serum. However, although these two degradative processes seem to be controlled similarly, they probably involve different mechanisms. The protease inhibitors leupeptin and chymostatin, which slowed overall proteolysis in nongrowing muscles and hepatocytes, reduced the degradation of the ACh receptor by 2--11-fold, but had no, or only slight, effects on the catabolism of average protein, even when overall proteolysis was accelerated by omitting serum and embryo extract. Chloroquine, an inhibitor of lysosomal function, also reduced the degradation of AChR, by about 10-fold, but decreased overall protein breakdown by only 20-30%. Incubation of myotubes at lower temperatures reduced both degradative processes, but affected the breakdown of the receptor to a greater extent. Thus the rate-limiting steps in these processes have different activation energies. Incubation with 2-deoxyglucose, an inhibitor of glycolysis, decreased the breakdown of average protein but not that of the receptor-toxin complex. However, the two degradative processes were sensitive to azide, an inhibitor of oxidative phosphorylation. Although the lysosome is the primary site for AChR degradation and perhaps for degradation of other surface proteins, the breakdown of most proteins in myotubes seems to involve a distinct proteolytic system requiring metabolic energy.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0021-9541
pubmed:author
pubmed:issnType
Print
pubmed:volume
107
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
185-94
pubmed:dateRevised
2011-11-17
pubmed:meshHeading
pubmed:year
1981
pubmed:articleTitle
Comparison of the control and pathways for degradation of the acetylcholine receptor and average protein in cultured muscle cells.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't