Molecular weight distribution of RNA fractionated on aqueous and 70% formamide surose gradients

T-cell mitogenesis stimulates the synthesis of a mRNA species coding for a 43-kDa peptide reactive with CM-H-9, a monoclonal antibody specific for placental isoferritin

In studying the changes that occur in concanavalin A-activated T lymphocytes, an mRNA species was discovered by hybridization of poly(A)+ mRNA with a human ferritin heavy chain cDNA probe. This ferritin mRNA, termed superheavy chain mRNA, differed from the known human ferritin heavy chain mRNAs by its larger size and degree of homology. The superheavy chain mRNA was isolated by sucrose-gradient centrifugation and translated in vitro in a cell-free system. The products obtained included two peptides (superheavy) of 43kDa that reacted with CM-H-9, a monoclonal antibody specific for placental isoferritin. De novo synthesis in intact transformed T cells revealed the synthesis of the superheavy chain peptides that were immunoprecipitated by anti-ferritin monoclonal antibody CM-G-8 and by placental isoferritin specific monoclonal antibody CM-H-9. The above results indicated that blast transformation of human T cells stimulated the appearance of a unique mRNA species that coded for a superheavy chain peptide associated with placental isoferritin, which was not detected in resting T cells.

Haemocyanin mRNA from arthropod and mollusc origin. Evidence for a multi-unit structure in mollusc haemocyanin mRNA

mRNA from two molluscs, the snail Levantina hierosolima and the cuttlefish Sepia officinalis, and one arthropod, the scorpion Leiurus quinquestriatus, were found to contain species that hybridize with an oligodeoxynucleotide sequence corresponding to the six-amino-acid sequence His-His-Trp-His-Trp-His postulated to carry binuclear copper in arthropod haemocyanins. The duplexes formed between the oligodeoxynucleotide and mRNA from Leiurus and Levantina had similar 'melting' temperatures, namely 46.5 and 44.5 degrees C respectively. The hybridizable mRNA species were identified with mRNA that codes for haemocyanin, Hc mRNA. Electrophoresis under denaturing conditions of Leiurus Hc mRNA gave a single band corresponding to 2.3 kb (kilobases), consistent with the value of 75 000 reported for the Mr of the polypeptide chain of arthropod haemocyanin. Electrophoresis of mollusc Hc mRNA yielded RNA bands corresponding to 9.4, 6.7, 4.0 and 1.7 kb for Levantina and 9.5, 2.8 and 1.7 kb for Sepia. The 9.4 and 9.5 kb species represent authentic Hc mRNA and are consistent with an Mr of 350 000 for molluscan haemocyanin polypeptide chain. The faster-moving RNA bands are attributed to Hc mRNA cleavage by nucleases during isolation of mRNA. Analysis of the electrophoretic band pattern indicates a multi-unit structure for mollusc Hc mRNA.

Human interferon gamma is encoded by a single class of mRNA

Polyadenylated RNA from human peripheral blood lymphocytes and spleen cells, treated with different inducers for IFN-gamma production, was fractionated on denaturing sucrose gradients. Two IFN-gamma mRNA peaks at 12S and 16S were consistently observed. Nucleotide sequence analysis of cDNA clones showed that the 12S IFN-gamma mRNA from the different sources is identical to the gel fractionated 18S IFN-gamma mRNA which gave rise to the IFN-gamma cDNA clone p69 (1). Nucleotide sequence analysis of several IFN-gamma cDNA clones showed the presence of a CGA (Arg) codon at position 140 of mature IFN-gamma in contrast with the CAA (Gln) codon, which is found in p69 (1). Specifically primed cDNA extension on total induced polyadenylated RNA revealed the presence of a single mRNA species having a 5' untranslated region of 125-130 nucleotides. The nucleotide sequence of this region has been obtained. These data suggest that a single human IFN-gamma gene, which has very little polymorphism, gives rise to a single size class of mRNA.