期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1992
卷号：89
期号：3
页码：895-899
DOI：10.1073/pnas.89.3.895
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Within the nucleus, pre-mRNA molecules are complexed with a set of proteins to form heterogeneous nuclear ribonucleoprotein complexes. A1, an abundant RNA binding protein present in these complexes, has been shown to bind selectively to single-stranded RNAs and destabilize base-pairing interactions. In this study.A1 is shown to promote the rate of annealing of complementary RNA strands greater than 300-fold under a wide range of salt concentration and temperature. Maximal annealing is observed under saturating or near saturating concentrations of protein, but annealing decreases sharply at both higher and lower concentrations of A1. Kinetic analysis shows that the rate of annealing is not strictly first or second order with respect to RNA at a ratio of protein/RNA that gives optimal rates of annealing. This result suggests that A1 protein may affect more than one step in the annealing reaction. Two polypeptides representing different domains of A1 were also examined for annealing activity. UP1, a proteolytic fragment that represents the N-terminal two-thirds of A1, displays very limited annealing activity. In contrast, a peptide consisting of 48 amino acid residues from the glycine-rich C-terminal region promotes annealing at a rate almost one-quarter that observed with intact A1. The RNA.RNA annealing activity of A1 may play a role in pre-mRNA splicing and other aspects of nuclear mRNA metabolism.
