TY - JOUR
T1 - Occurrence of cysteinyl transfer ribonucleic acid with a blocked α-amino group in rabbit reticulocytes
AU - Pawelek, John
AU - Godchaux, Walter
AU - Grasso, Joseph
AU - Skoultchi, Athur I.
AU - Eisenstadt, Jerome
AU - Lengyel, Peter
N1 - Funding Information:
We thank Drs. M. Bodanszky, W. Konigsberg and D. S61t for their helpful advice and Drs. J. Lapointe and D. $611 for a preparation of tRNA adenylyltrans-ferase from E. coli. This study was supported by research grants (GM 137o 7, AM o7189, AM 11896 ) from the National Institutes of Health, a postdoctoral fellowship (PF-444) from the American Cancer Society to J. P., a postdoctoral fellowship from the National Cancer Institute to A. I. S., and a research career development award (IK 3-17, 572) from the National Institutes of Health to J. G.
PY - 1971/3/11
Y1 - 1971/3/11
N2 - 1. Rabbit reticulocytes or reticulocyte extracts incorporate cysteine into cysteinyl transfer ribonucleic acid (Cys-tRNA) having a blocked α-amino group (X-Cys-rRNA). The lack of a free α-amino group is revealed in the electrophoretic characteristics of X-cysteinyladenosine (X-Cys-A) obtained from X-Cys-tRNA by treatment with pancreatic ribonuclease, and in the failure of the X-Cys-A to react with acetic anhydride. The electrophoretic characteristics of X-Cys-A and its reactivity with diazomethane indicate that the blocking group X might have a free carboxyl group. X-Cys-A does not react with iodoacetate, possibly indicating that its sulfhydryl group is blocked. 2. Both high and low molecular weight fractions of the reticulocyte extract (obtained by fractionation by gel filtration through a Sephadex G-25 column) are needed for converting Cys-tRNA into X-Cys-tRNA. X-Cys-tRNA was not found in Escherichia coli extracts, but E. coli Cys-tRNA is converted to X-Cys-tRNA when added to a reticulocyte extract. 3. NaF is thought to inhibit a step in peptide chain initiation and to lead to the accumulation of initiation complexes (W. Hoerz and K. S. McCarthy, Proc. Natl. Acad. Sci. U.S., 63 (1969) 1206). A tRNA species involved in chain initiation in reticulocytes is tRNAMetf. Intact reticulocytes treated with NaF contain about 7 times more X-Cys-tRNA and 4 times more tRNAMetf (at least partially acylated with methionine) bound to ribosomes than control cells. The amount bound to ribosomes of several other aminoacyl-tRNA's tested (including Cys-tRNA), however, decreases upon treatment with NaF. 4. The structure, biosynthesis, and function of X-Cys-tRNA remain to be established.
AB - 1. Rabbit reticulocytes or reticulocyte extracts incorporate cysteine into cysteinyl transfer ribonucleic acid (Cys-tRNA) having a blocked α-amino group (X-Cys-rRNA). The lack of a free α-amino group is revealed in the electrophoretic characteristics of X-cysteinyladenosine (X-Cys-A) obtained from X-Cys-tRNA by treatment with pancreatic ribonuclease, and in the failure of the X-Cys-A to react with acetic anhydride. The electrophoretic characteristics of X-Cys-A and its reactivity with diazomethane indicate that the blocking group X might have a free carboxyl group. X-Cys-A does not react with iodoacetate, possibly indicating that its sulfhydryl group is blocked. 2. Both high and low molecular weight fractions of the reticulocyte extract (obtained by fractionation by gel filtration through a Sephadex G-25 column) are needed for converting Cys-tRNA into X-Cys-tRNA. X-Cys-tRNA was not found in Escherichia coli extracts, but E. coli Cys-tRNA is converted to X-Cys-tRNA when added to a reticulocyte extract. 3. NaF is thought to inhibit a step in peptide chain initiation and to lead to the accumulation of initiation complexes (W. Hoerz and K. S. McCarthy, Proc. Natl. Acad. Sci. U.S., 63 (1969) 1206). A tRNA species involved in chain initiation in reticulocytes is tRNAMetf. Intact reticulocytes treated with NaF contain about 7 times more X-Cys-tRNA and 4 times more tRNAMetf (at least partially acylated with methionine) bound to ribosomes than control cells. The amount bound to ribosomes of several other aminoacyl-tRNA's tested (including Cys-tRNA), however, decreases upon treatment with NaF. 4. The structure, biosynthesis, and function of X-Cys-tRNA remain to be established.
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U2 - 10.1016/0005-2787(71)90582-X
DO - 10.1016/0005-2787(71)90582-X
M3 - Article
C2 - 4928711
AN - SCOPUS:0015219423
SN - 0005-2787
VL - 232
SP - 289
EP - 305
JO - BBA Section Nucleic Acids And Protein Synthesis
JF - BBA Section Nucleic Acids And Protein Synthesis
IS - 2
ER -