RESUMO
Under protonation of the single-stranded polyadenylic acid so called "frozen" form arises simultaneously with formation of two double-stranded forms. It has been shown that a portion of the polyadenylic acid "frozen" form increases with the size of poly(A) and ionic strength of solution, i. e. with an increase of polymer chain flexibility. These findings may be considered as evidences in favor of our earlier supposition on poly(A) ability to fold with formation of intramolecular double-stranded helices. Ten years ago we also proposed a hypothesis that such double-stranded helices can be formed in poly(A) tracts of cellular RNAs and they can participate in several biological processes. An analysis of literature data published later evidences for the hypothesis adequacy and shows that it still remains urgent.
Assuntos
Conformação de Ácido Nucleico , Poli A/química , RNA de Cadeia Dupla/química , RNA Mensageiro/química , Eletroforese em Gel de Ágar , Modelos Moleculares , Concentração Osmolar , Poli A/biossíntese , Proteínas de Ligação a Poli(A)/química , Poliadenilação , RNA de Cadeia Dupla/biossíntese , RNA Mensageiro/biossínteseRESUMO
A selective interaction of ATA with RNA, unlike DNA, when isolating nucleic acids from plant materials was established. The data concerning the binding strength of highly purified RNAATA and DNAATA preparations to nitrocellulose and nylon filters under conditions of high ionic strength are presented. The interrelation of ATA RNA-tropism and absence of adsorption capability of chemical modified RNAATA the backbone was observed. Using IR spectroscopy under the procedure of multi-broken complete light reflection, a formation of ATA and RNA complex was fixed via phosphoric-ether bond (P-O-C), which was absent in the case of DNAATA. The obtained data raise the problem of RNAATA application in molecular biology experiments.
Assuntos
Ácido Aurintricarboxílico/metabolismo , DNA/isolamento & purificação , RNA/metabolismo , Espectrofotometria Infravermelho/métodos , Colódio/metabolismo , Kalanchoe/química , Nylons/metabolismo , Concentração Osmolar , RNA/isolamento & purificação , RNA de Plantas/isolamento & purificação , RNA de Plantas/metabolismoRESUMO
Specific cleavage of transcript by a complex of multisubunit proteins is the first stage of polyadenylation of eukaryotic pre-mRNAs. The main participant of this reaction--endonuclease--is not discovered yet. However it is known that proteins CPSF-30 (mammalian) and Yth 1p (yeast) are homologues of the drosofila protein clipper (CLP), which displays endoribonucleolytic activity. In the N-terminal region all three proteins contain five copies of CCCH zinc finger motif that are associated with nucleolytic activity in the case of CLP. Literature data on the three above-mentioned proteins has been analysed. The results of these works do not contradict the hypothesis that exactly CPSF-30 and its homologues are the actual nucleases that cleave pre-mRNA in the process of polyadenylation.