Complete sequence of ovine alpha s2-casein messenger RNA.

The primary structure of mRNA coding for ovine alpha s2 casein has been determined by chemical sequencing of three cDNA clones and the primer extension products of the longest one. The mRNA was 1,024 nucleotides long, excluding the poly(A) tail. The length of the 5' noncoding, coding and 3' noncoding regions was 53, 669 and 302 nucleotides, respectively.

[Control of the initiation step in eukaryotic cells].

This article presents some arguments in favor of post-transcriptional regulation of protein synthesis. The macromolecules inducing initiation have been described. The control mechanisms of initiation have been studied in reticulocytes and cells treated with interferon.

Purification and properties of the major tRNAHis from sheep liver.

The major isoacceptor of tRNAHis from sheep liver was purified. Two different methods were described which both took advantage of the presence of the hypermodified Q nucleotide in this tRNA. In the first procedure, CNBr treatment of tRNA which was previously enriched in tRNAHis greatly increased the efficiency of the subsequent chromatographic steps.

Correlation between the presence of tRNA His GUG and the erythropoietic function in foetal sheep liver.

Histidyl-tRNAs from foetal and adult sheep liver were compared to their reticulocyte counterparts. The combination of various techniques revealed the existence of two histidyl-tRNA species in reticulocytes, one of which was not retained on acetylated DBAE-cellulose columns and was guanylatable. Three histidyl-tRNA isoacceptors were identified in foetal liver.

Biochemical research on oogenesis. Nucleotide sequence of initiator tRNA from oocytes and from somatic cells of Xenopus laevis.

The nucleotide sequence of initiator tRNA, tRNAfMet, from vitellogenic oocytes of Xenopus laevis was determined. The sequence was deduced from analysis of all T1 and pancreatic oligonucleotides and comparison with the sequence of initiator tRNA from other animal species. At least 80% of all initiator tRNA molecules from oocytes have the same nucleotide sequence.

Replacement of the sequence G-T-phi-C-G(A)- by G-A-U-C-G- in initiator transfer RNA of rabbit-liver cytoplasm.

Eukaryotic cytoplasmic initiator tRNAs lack the sequence G-T-Psi-C-G(A)-, which is in every tRNA of known sequence that is active in protein biosynthesis. In initiator tRNA of yeast cytoplasm, which is the only eukaryotic initiator tRNA of known sequence, this sequence is replaced by G-A-U-C-G-. We now report the sequence of a 30-nucleotide-long, 3'-terminal fragment of cytoplasmic initiator tRNA of rabbit liver obtained by specific cleavage of the tRNA at the site occupied by the modified nucleoside, 7-methyl guanosine.

Evidence for the absence of the G-T-psi-C sequence from two mammalian initiator transfer RNAs.

Analyses were performed on the purified initiator tRNA from rabbit liver to test for the presence of Psip and Tp in this molecule. Neither of these nucleotides could be detected after hydrolysis by piperidine, NaOH, or T2 RNase. Similarly digestion with venom phosphodiesterase plus phosphatase failed to release any pseudourdine or ribothymidine.

[Not Available].

This paper describes an attempt to find a difference between the patterns of methylation of E. coli tRNA by extracts of two mouse tissues. Two samples of tRNAs, methylated in two separate experiments with extracts of myeloma and of liver in presence of either 14C or 3H S-Adenosyl-L-Methionine, were pooled and fractionated together on a RPC column.