Alternative splicing expression of U1 snRNP 70K gene is evolutionary conserved between different plant species.

A U1-snRNP--specific 70K (U1-70K) protein is intricately involved in both constitutive and alternative splicing of pre-mRNAs. Here, we report cDNA and cognate genomic sequences of the U1-70K gene of maize and rice. The maize and rice U1-70K genes bear strong similarity to the Arabidopsis gene and each encode three transcripts in roots and shoots. Alternative splicing produces two transcripts from each gene in addition to the mRNA encoding the wild type protein. In both cases, selective inclusion of intron 6 or utilization of a cryptic donor site within intron 6 sequence generates the two alternatively spliced transcripts. This evolutionary conservation of splicing patterns between different plant species suggests an important biological function for alternative splicing in the expression of U1-70K gene.