Histone messenger RNA from HeLa cells: evidence for modified 5' termini.
The distribution of [3H]methyl radioactivity in cytoplasmic histone mRNA, isolated during the DNA synthetic (S) phase of the HeLa S3 cell cycle, has been investigated. Evidence is presented that approximately 30% of the radioactivity is in m7GpppXmpYp oligonucleotides, where Xm represents 2'-O-methylated adenosine and guanosine with a molar ratio of 4:1, respectively. The remainder of the radioactivity is present as m7GpppCmpYmpZp oligonucleotides, where Xm is again 2'-O-methylated adenosine and guanosine (4:1) and where ym represents 2'-O-methylated adenosine, guanosine, cytidine, and uridine with ratios of 2:1:1:1, respectively. While 48.6% of the [3H]methyl radioactivity was present as N6-methyladenosine in poly(adenylic acid)-terminated mRNA from S-phase cells, no evidence for N6-methyladenosine was found in histone mRNA. It thus appears that histone mRNA which lacks 3'-terminal poly(adenylic acid) sequences and functions on cytoplasmic polyribosomes during a limited protion of the cell cycle is capped but lacks internal-modified nucleosides.
D002455:Cell Division; D004261:DNA Replication; D006367:HeLa Cells / Q000378:metabolism*; D006657:Histones / Q000096:biosynthesis*; D011061:Poly A; D012333:RNA, Messenger / Q000378:metabolism; D012263:Ribonucleosides / Q000032:analysis
D006657:Histones; D012333:RNA, Messenger; D012263:Ribonucleosides; D011061:Poly A