title: [Structure of nuclear pre-mRNA. XIII. Hybridization properties of triphosphorylated 5'-end fragments].
abstract: Triphosphorylated 5'-end fragments about 100 nucleotides long were prepared from purified nuclear pre-mRNA using a modified hydroxyapatite method. These fragments as well as fragments of total pre-mRNA were polyadenylated by ATP:RNA adenyl-transferase and used as templates for the synthesis of [32P]cDNA by reverse transcriptase in the presence of an oligo(dT)-primer, cDNA transcribed from total fragments of pre-mRNA and from 5'-end fragments (5'-cDNA) were hybridized with excess of nuclear pre-mRNA. The extent of hybridization was 65-70 and 80-85% in different experiments. 18% of total cDNA and 35% of 5'-cDNA hybridized with mRNA from polysomes. A high homology between mRNA and triphosphorylated 5'-ends of pre-mRNA may be explained in the terms of splicing. The sequences adjacent to the triphosphorylated 5'-ends of pre-mRNA represent a specific class with complexity about 2.10(5) nucleotides. Less than 30% of 5'-cDNA hybridized with intermediately repetitive DNA, while the main portion hybridized with unique DNA sequences. About 15% of 5'-cDNA contain oligo (dA) sequences, originated from oligo (U) in the pre-mRNA.
mesh_terms: D000255:Adenosine Triphosphate; D001483:Base Sequence; D004926:Escherichia coli / Q000378:metabolism; D007700:Kinetics; D009693:Nucleic Acid Hybridization; D009694:Nucleic Acid Precursors / Q000378:metabolism; D011061:Poly A / Q000096:biosynthesis; D011062:Polynucleotide Adenylyltransferase / Q000378:metabolism; D011132:Polyribosomes / Q000378:metabolism; D012322:RNA Precursors; D012333:RNA, Messenger / Q000096:biosynthesis / Q000378:metabolism; D012194:RNA-Directed DNA Polymerase / Q000378:metabolism
chemical_list: D009694:Nucleic Acid Precursors; D012322:RNA Precursors; D012333:RNA, Messenger; D011061:Poly A; D000255:Adenosine Triphosphate; D011062:Polynucleotide Adenylyltransferase; D012194:RNA-Directed DNA Polymerase
vernacular_title: Struktura iadernoĭ pre-mRNK. XII. Gibridizatsionnye svoĭstva trifosforilirovannykh 5'-kontsevykh fragmentov.