Hel-N2: a novel isoform of Hel-N1 which is conserved in rat neural tissue and produced in early embryogenesis.

Hel-N1 is a neural-specific RNA-binding protein which is highly conserved over evolution. The data presented here demonstrate alternative 5' splicing of Hel-N1 mRNA, characterized by the insertion of a novel 91-bp exon. The resultant isoform, Hel-N2, has a potentially expanded N-terminal region of 29 amino acids when compared to Hel-N1. Reverse transcription (RT)-PCR cloning data indicate that homologues (Rel-N1 and Rel-N2) exist in rat neural tissue where there is 96% conservation at the nucleotide level. RT-PCR analysis of rat embryonic tissue RNA indicates that this splicing event occurs as early as day 12 of embryogenesis. The temporal pattern of expression of Rel-N1 and Rel-N2 resembles that of the Drosophila melanogaster homologue, elav, and supports the prior notion that these mammalian counterparts participate in early neural development.