The Poly(adenylic acid) Sequence of Mouse Globin Messenger RNA

Abstract

Mouse globin messenger RNA has been degraded by ribonuclease T, to give poly(adeny1ic acid) fragments of two size classes which run electrophoretically with standard RNA molecules approximately 75 and 50 nucleotides long. These contain no internal ribonucleotides other than adenosine and occur at the 3'-end of the mRNA molecule. The probable sequence to the 5'-side of the poly(A) tract is -G-C. Attempts to separate the DL and B mRNA activities by formamide gradient elution from poly(U)-Sepharose were unsuccessful.The evidence is more compatible with a post-transcriptional end-addition mechanism for t,he synthesis of the poly(adeny1ic acid) region of messenger RNA than a transcriptional mechanism.

Isolation and Characterization of Highly Purified Globin Messenger RNA from Anaemic-Rabbit Spleen

“…No significant difference in poly(A) content could be detected between spleen and reticulocyte globin mRNA. The mean length of 50 nucleotides that we found for the poly(A) tracts from both globin mRNA preparations is in close agreement with previous estimates for poly(A) size in globin mRNA from rabbit reticulocytes [1,27] and from mouse reticulocytes [19,28]. As spleen 9-S RNA preparations might be contaminated by non-messenger RNA, the 7.8% of poly(A) that we found in this fraction could correspond to longer poly(A) sequences than 50 nucleotides.…”

Poly(A) Tail Shortening by a Mammalian Poly(A)-specific 3′-Exoribonuclease

“…Such a distribution was described in the steady state population of globin mRNA (23)(24)(25) and, less pronounced, also in mRNAs for epidermal growth factor and glyceraldehyde-3Ј-phosphate dehydrogenase (26,27). Similar molecules were identified as deadenylation intermediates of the gro-␣ cytokine mRNA (27).…”

The nature of the 5'-linked 5' nucleotide sequence at the 5' end of rabbit globin messenger ribonucleic acid

“…The peaks in area I in Fig. 1(a) contain ApA-iNicHz and ApApa-iNicHz, when iNicHz is used to denote the isonicotinoyl residue, and are most probably caused by pancreatic ribonuclease digestion in low salt of an oligo(A) sequence (pA).-iNicHz (Mansbridge et al, 1974). Further, when the peak in area IV, obtained by ribonuclease T1 digestion, was digested with pancreatic ribonuclease in low salt, the diand trioligo(A) sequences which could be obtained by digestion ofisoniazid-labelled mRNA with pancreatic ribonuclease alone were also found.…”