hnRNP A1 and hnRNP H can collaborate to modulate 5′ splice site selection

A different binding site for hnRNP H can modulate splice site selection. (A) Sequence of HBS3 and the hnRNP A1 binding site CE1a (left). Structure of the pre-mRNAs containing hnRNP H binding sites (right). (B) hnRNP H binds more efficiently to HBS3 compared with hnRNP A1. Filter binding assay using ³²P-labeled HBS3 or CE1a RNAs. His-tagged hnRNP H or A1 proteins were used at 0, 0.5, 1, and 2 μM. (C) In vitro splicing assays and RT-PCR amplification. The distal (D), and proximal (P) products as well as the pre-mRNAs (Pre) are indicated. For each reaction, the percentage of proximal product is indicated in the graph.