Linked Life Data

1429850

Source:http://linkedlifedata.com/resource/pubmed/id/1429850

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1992-12-1
pubmed:abstractText
A protein carboxyl methyltransferase (PCMT), which specifically modifies atypical protein L-isoaspartyl and D-aspartyl residues, is widely distributed in eucaryotic cells, but the factors that regulate its activity in vivo have not been identified. It has been proposed that the PCMT initiates the repair of structurally damaged proteins. To test the possibility that the concentration of structurally abnormal cellular proteins affects PCMT activity, protein carboxyl methylation reactions were studied in HeLa cells exposed to various stresses that increase the extent of protein unfolding in cells. Protein carboxyl methylation rates increased 70-80% during incubations at 42 degrees C and remained elevated for periods of up to 8 hr. This sustained increase was greater than that predicted from thermal effects on the enzyme alone and may reflect the exposure of atypical aspartyl sites as proteins unfold as well as increased rates of protein deamidation and isomerization at elevated temperatures. Methylation rates showed no increases following 12 hr incubations with the amino acid analogs L-azetidine-2-carboxylic acid or L-canavanine. Northern blot analysis of RNA preparations from control and stressed cells revealed three major transcripts for the PCMT in HeLa cells, which are 1.6, 2.6, and 4.5 kb in length. The concentrations of all three transcripts decreased by approximately 20% from control levels during heat shock. No changes in PCMT transcript concentrations were observed during incubation with the amino acid analogs. By contrast, large increases in the concentrations of hsp70 and ubiquitin transcripts were observed following either heat or chemical stresses. The results demonstrate that the PCMT is a constitutive component of cells whose function is required under normal conditions as well as during stress conditions, which accelerate structural damage to cellular proteins.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0021-9541
pubmed:author
pubmed:issnType
Print
pubmed:volume
153
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
297-304
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1992
pubmed:articleTitle
Methylation of atypical protein aspartyl residues during the stress response of HeLa cells.
pubmed:affiliation
Worcester Foundation for Experimental Biology, Shrewsbury, Massachusetts 01545.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.