Abstract
Eukaryotic initiation factor 5 (eIF-5), which specifically catalyzes the joining of a 60 S ribosomal subunit to a 40 S initiation complex to form a functional 80 S initiation complex, has been purified from ribosomal salt wash proteins of calf liver. The purified factor exhibits only one polypeptide band of M(r) = 62,000 following electrophoresis in 10% polyacrylamide gels in the presence of sodium dodecyl sulfate. The native protein has a sedimentation coefficient of 4.2 S and a Stokes radius of 33 Å which is consistent with eIF-5 being a monomeric protein of M(r) = 58,000-62,000. Less pure preparations of eIF-5 elute in gel filtration columns with an apparent M(r) of 160,000-180,000 presumably due to association of eIF-5 with other high molecular weight proteins since eIF-5 activity present in such preparations can also be shown by gel electrophoretic separation under denaturing conditions to be associated with a 62,000-dalton protein. Furthermore, eIF-5 purified from calf liver extracts with or without a number of protease inhibitors is indistinguishable with regard to molecular weight and final specific activity of purified preparations. The purified factor catalyzes the hydrolysis of GTP present in 40 S initiation complexes in the absence of 60 S ribosomal subunits. The presence of 60 S ribosomal subunits neither stimulates nor inhibits the hydrolysis of GTP in the absence of Met-tRNA(f) or other components required for 40 S initiation complex formation. It can be calculated that 1 pmol of eIF-5 protein can catalyze the formation of at least 10 pmol of 80 S initiation complex under the conditions of in vitro initiation reactions.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 2132-2139 |
| Number of pages | 8 |
| Journal | Journal of Biological Chemistry |
| Volume | 260 |
| Issue number | 4 |
| State | Published - 1985 |
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ASJC Scopus subject areas
- Biochemistry
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Eukaryotic initiation factor 5 from calf liver is a single polypeptide chain protein of M(r) = 62,000. / Raychaudhuri, P.; Chaudhuri, A.; Maitra, U.
In: Journal of Biological Chemistry, Vol. 260, No. 4, 1985, p. 2132-2139.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Eukaryotic initiation factor 5 from calf liver is a single polypeptide chain protein of M(r) = 62,000
AU - Raychaudhuri, P.
AU - Chaudhuri, A.
AU - Maitra, U.
PY - 1985
Y1 - 1985
N2 - Eukaryotic initiation factor 5 (eIF-5), which specifically catalyzes the joining of a 60 S ribosomal subunit to a 40 S initiation complex to form a functional 80 S initiation complex, has been purified from ribosomal salt wash proteins of calf liver. The purified factor exhibits only one polypeptide band of M(r) = 62,000 following electrophoresis in 10% polyacrylamide gels in the presence of sodium dodecyl sulfate. The native protein has a sedimentation coefficient of 4.2 S and a Stokes radius of 33 Å which is consistent with eIF-5 being a monomeric protein of M(r) = 58,000-62,000. Less pure preparations of eIF-5 elute in gel filtration columns with an apparent M(r) of 160,000-180,000 presumably due to association of eIF-5 with other high molecular weight proteins since eIF-5 activity present in such preparations can also be shown by gel electrophoretic separation under denaturing conditions to be associated with a 62,000-dalton protein. Furthermore, eIF-5 purified from calf liver extracts with or without a number of protease inhibitors is indistinguishable with regard to molecular weight and final specific activity of purified preparations. The purified factor catalyzes the hydrolysis of GTP present in 40 S initiation complexes in the absence of 60 S ribosomal subunits. The presence of 60 S ribosomal subunits neither stimulates nor inhibits the hydrolysis of GTP in the absence of Met-tRNA(f) or other components required for 40 S initiation complex formation. It can be calculated that 1 pmol of eIF-5 protein can catalyze the formation of at least 10 pmol of 80 S initiation complex under the conditions of in vitro initiation reactions.
AB - Eukaryotic initiation factor 5 (eIF-5), which specifically catalyzes the joining of a 60 S ribosomal subunit to a 40 S initiation complex to form a functional 80 S initiation complex, has been purified from ribosomal salt wash proteins of calf liver. The purified factor exhibits only one polypeptide band of M(r) = 62,000 following electrophoresis in 10% polyacrylamide gels in the presence of sodium dodecyl sulfate. The native protein has a sedimentation coefficient of 4.2 S and a Stokes radius of 33 Å which is consistent with eIF-5 being a monomeric protein of M(r) = 58,000-62,000. Less pure preparations of eIF-5 elute in gel filtration columns with an apparent M(r) of 160,000-180,000 presumably due to association of eIF-5 with other high molecular weight proteins since eIF-5 activity present in such preparations can also be shown by gel electrophoretic separation under denaturing conditions to be associated with a 62,000-dalton protein. Furthermore, eIF-5 purified from calf liver extracts with or without a number of protease inhibitors is indistinguishable with regard to molecular weight and final specific activity of purified preparations. The purified factor catalyzes the hydrolysis of GTP present in 40 S initiation complexes in the absence of 60 S ribosomal subunits. The presence of 60 S ribosomal subunits neither stimulates nor inhibits the hydrolysis of GTP in the absence of Met-tRNA(f) or other components required for 40 S initiation complex formation. It can be calculated that 1 pmol of eIF-5 protein can catalyze the formation of at least 10 pmol of 80 S initiation complex under the conditions of in vitro initiation reactions.
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UR - http://www.scopus.com/inward/citedby.url?scp=0021912927&partnerID=8YFLogxK
M3 - Article
C2 - 3844405
AN - SCOPUS:0021912927
VL - 260
SP - 2132
EP - 2139
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 4
ER -