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：1990
卷号：87
期号：16
页码：6253-6257
DOI：10.1073/pnas.87.16.6253
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The 5' splice site of a pre-mRNA is recognized by U1 small nuclear ribonucleoprotein particles (snRNP) through base pairing with the 5' end of U1 small nuclear RNA (snRNA). Single-base substitutions within a 9-nucleotide 5'-splice-site sequence can abolish or attenuate use of that site and, in higher eukaryotes, can also activate nearby "cryptic" 5' splice sites. Here we show that the effects of single-base substitutions within a 5' splice site can be completely or partially suppressed by cis mutations that improve the overall complementarity of the site to U1 snRNA. We further show that in the presence of the normal 5' splice site, a cryptic 5' splice site can be activated by increasing its complementarity to U1 snRNA. U1 snRNP binding experiments confirm that cryptic 5' splice sites are activated when their affinity for U1 snRNP approaches that of the authentic 5' splice site. Based upon these results, we propose a spliceosome competition model for 5'-splice-site selection and cryptic 5'-splice-site activation. We discuss our results with regard to the factors involved in 5'-splice-site recognition.
