Characterization of wheat germ protein synthesis initiation factor eIF-4C and comparison of eIF-4C from wheat germ and rabbit reticulocytes.
Eukaryotic protein synthesis initiation factor (eIF)-4C was purified from wheat germ and the molecular weight was calculated to be approximately 19,000 by SDS-polyacrylamide gel electrophoresis. A similar molecular weight was determined by gel filtration chromatography indicating that wheat germ eIF-4C is functional as a single polypeptide chain. An efficient in vitro translation system dependent upon the addition of eIF-4C was developed. This system was used to determine the concentrations of eIF-4C required for the half-maximal rate of translation of satellite tobacco necrosis virus RNA, alfalfa mosaic virus RNA 4, and barley alpha-amylase mRNA. No significant differences in the concentrations of eIF-4C required for the translation of these mRNAs were observed, although differences were noted for eIF-4A and eIF-4F. This finding suggests that eIF-4C is not involved in the binding of mRNA to 40 S ribosomal subunits. In heterologous assays, rabbit reticulocyte eIF-4C was as active as wheat germ eIF-4C in the wheat germ eIF-4C-dependent system. In addition, wheat germ eIF-4C substituted for rabbit reticulocyte eIF-4C in in vitro assay systems from rabbit reticulocytes. These results indicate that eIF-4C from wheat and rabbit contain conserved functional domains.
Timmer
R T
RT
Department of Chemistry and Biochemistry, University of Texas, Austin 78712.
Lax
S R
SR
Hughes
D L
DL
Merrick
W C
WC
Ravel
J M
JM
Browning
K S
KS
D000818:Animals; D002848:Chromatography, DEAE-Cellulose; D004591:Electrophoresis, Polyacrylamide Gel; D015977:Eukaryotic Initiation Factor-1; D010448:Peptide Initiation Factors / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics; D011817:Rabbits; D012156:Reticulocytes / Q000737:chemistry*; D014908:Triticum / Q000737:chemistry*
D015977:Eukaryotic Initiation Factor-1; D010448:Peptide Initiation Factors; D012333:RNA, Messenger; C026022:eukaryotic peptide initiation factor-1A