Linked Life Data

1247535

Source:http://linkedlifedata.com/resource/pubmed/id/1247535

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1976-4-29
pubmed:abstractText
Earlier work has shown that the inhibition by pactamycin (PM) of polypeptide chain initiation in reticulocyte extracts is associated with (1) a defect in the joining of the 60S subunit to the smaller initiation complex to form an 80S complex ("joining reaction") (Kappen, L. S., Suzuki, H., and Goldberg, I. H. (1973), Proc. Natl. Acad. Sci. U.S.A. 70, 22) and (2) a block after the synthesis of the initial dipeptide (Kappen, L. S., and Goldberg, I. H. (1973), Biochem. Biophys. Res. Commun. 54, 1083). The relative contributions of these two effects to the action of PM and their relationship to one another were evaluated in a system employing sparsomycin that permits both initiation at a certain number of initiation sites and limited oligopeptide formation without termination and release. The degree to which PM blocks the "joining reaction" and leads to the accumulation of 48S initiation complexes that either remain free or are bound to polysomes without the corresponding 60S subunit ("half-mers") was estimated by treatment of polysomes with RNase. Met-tRNAfMet binding factors are required to stabilize the RNase-generated 48S complexes. Under conditions where the initiation factor required for the "joining reaction" functions catalytically, presumably by cycling on and off initiation complexes, PM usually inhibits 80S complex formation 50-70%. Where "joining" is not limiting (presence of at least stoichiometric amounts of joining factor or high Mg2+ concentration) PM leads to the maximal accumulation of the initial dipeptide, Met-Val, in the P-site on the ribosome, indicating a block in a subsequent step in elongation. Binding studies with [3H]PM and the inability of PM to inhibit elongation of preformed Met-Val indicate that PM must interact with the ribosomes at an early stage of initiation. Taken together these data are compatible with the suggestion that PM does not interfere with the ribosomal "joining reaction" per se, but prevents the release and reuse of the joining factor, and in so doing blocks a step in elongation after formation of the initial dipeptide and its translocation to the P-site on the ribosome.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
24
pubmed:volume
15
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
811-8
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1976
pubmed:articleTitle
Analysis of the two steps in polypeptide chain initiation inhibited by pactamycin.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.