Abstract
The functional properties of preparations of protein synthesis initiation factor eIF-2 which lack the β-subunit (as confirmed immunologically) were compared with those of the heterotrimeric factor. The former can bind guanine nucleotides but not initiator tRNA, and also exhibits a substantially reduced rate of initiation factor eIF-2B-mediated GDP/GTP-exchange.
| Original language | English |
|---|---|
| Pages (from-to) | 117-121 |
| Number of pages | 5 |
| Journal | BBA - Gene Structure and Expression |
| Volume | 1174 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published or Issued - 18 Jul 1993 |
| Externally published | Yes |
Keywords
- Guanine nucleotide
- Initiation factor
- Protein synthesis
ASJC Scopus subject areas
- Structural Biology
- Biophysics
- Biochemistry
- Genetics
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}
In: BBA - Gene Structure and Expression, Vol. 1174, No. 1, 18.07.1993, p. 117-121.
Research output: Contribution to journal › Article › peer-review
TY - JOUR
T1 - The role of the β-subunit of initiation factor eIF-2 in initiation complex formation
AU - Flynn, Andrea
AU - Oldfield, Susan
AU - Proud, Christopher G.
N1 - Funding Information: Severagl roupsh aved emonstratead s pecificin terac-tion betweene IF-2 and messengeRrN A (see Ref. 1 for a review).T he translationaelf ficiencyo f certainm es-sagesa ppeartso correlatew ith the abilityo f the mRNA to bind elF-2. There is evidenceto suggesat role for the /3-subuniitn this interaction\[ 9,28\T].h e inabilityo f elF-2 to bind Met-tRNA i and mRNA simultaneously also suggeststh at the two interactionos ccur on the same subunit(s)\[ 29,30\]I.n this contexti t should be noted that Gonsky et al. \[10\h] ave recentlyr esolved elF-2/3 from the other two subunitsb y chromatography of the denaturedfa ctor on ATP-agaroseo, n which it is retained,a nd have shown that isolated /3-subunict anbind mRNA. The availabilityo f a prepa-rationo f elF-2 which lacks the/3-s ubunitw ill facilitate the studyo f its role in interactionws ith mRNA. Since preparationdse voido f elF-2/3 still bind guanine nucleotidesw, e have also been able to study whethert he absenceo f this polypeptidien fluencesth e ability of elF-2B to mediatee xchangeo f bound GDP for GTP. As showni n Fig. 4, the initial rate of elF-2B-promotedlo ss of \[3H\]GDwPa s substantiallfya sterf or complexefso rmedw ith trimerice lF-2 as comparedto complexefso rmedw ith elF-2 lackingt he /3-subunitI.n the experimensth own,the differencew as at least 6-fold. This overallp atternw as seenw ith severapl reparations of both 'two' and 'three' subunit elF-2, and similar amountso f complexw ere formedf or two-subunit and trimeric elF-2 in each experimentI.n each experimensti milarrates of spontaneou(si. e., elF-2B-independenet)x changoef GDP for GTP were seenf or the heterotrimearn d for factor lackingt he /3-subunit. The findingt hatelF-2 lackingt he/3-subuneitx hibitsa lower rate of elF-2B-mediatendu cleotide-exchaning-e dicatest hat this subunitp lays a role in this process, perhapsb y interactinwg ith the exchangefa ctor.H ow-ever this interactionm ustp resumablayl soi nvolvee iF-2a, since phosphorylatioonf this subunit influences elF-2B-mediatendu cleotide-exchanagned since mutations in elF-2a at loci other than the phosphorylation site (i.e., Ser-48 rather than Ser-51) also appear to affect the exchangep rocess\ [31\]I.n Saccharomyces cerevisiaem, utationsin the SUI2 and SUI3 alleles, which code for elF-2a and /3, respectivelya,r e able to derepresse xpressiono f GCN4 under non-starvation conditions\[ 32\]T. he possibilityt hat this is due to a direct effect on elF-2B activity is supportedb y the evidencep resentedh ere for an interactionb etween elF-2/3 and the guaninen ucleotide-exchanfagcet or. This work was supportedb y a Project Grant from the Medical ResearchC ouncil (to CGP). AF is the recipiento f a ResearchS tudentshifpr om the Medical ResearchC ouncil.A nti-elF-2/3a ntibodiews eregener-ously providedb y Drs. U.-A. Bommer (St. Georges, London)a nd R. Jagus (BaltimoreM, D). The anti-elF-2a monoclonaal ntibodyw as provided by Dr. E.C. Henshaw(,R ochesteCr ancerC entre,N Y).
PY - 1993/7/18
Y1 - 1993/7/18
N2 - The functional properties of preparations of protein synthesis initiation factor eIF-2 which lack the β-subunit (as confirmed immunologically) were compared with those of the heterotrimeric factor. The former can bind guanine nucleotides but not initiator tRNA, and also exhibits a substantially reduced rate of initiation factor eIF-2B-mediated GDP/GTP-exchange.
AB - The functional properties of preparations of protein synthesis initiation factor eIF-2 which lack the β-subunit (as confirmed immunologically) were compared with those of the heterotrimeric factor. The former can bind guanine nucleotides but not initiator tRNA, and also exhibits a substantially reduced rate of initiation factor eIF-2B-mediated GDP/GTP-exchange.
KW - Guanine nucleotide
KW - Initiation factor
KW - Protein synthesis
UR - https://www.scopus.com/pages/publications/0027244179
U2 - 10.1016/0167-4781(93)90105-M
DO - 10.1016/0167-4781(93)90105-M
M3 - Article
C2 - 8334162
AN - SCOPUS:0027244179
SN - 0167-4781
VL - 1174
SP - 117
EP - 121
JO - BBA - Gene Structure and Expression
JF - BBA - Gene Structure and Expression
IS - 1
ER -