Characterization of two promoters of the Xenopus laevis elrD gene.

The Xenopus laevis elrD gene belongs to the multigenic elav/Hu family. elrD is exclusively expressed in neural cells, where it could be involved in the posttranscriptional control of mRNAs. Here we report the isolation and characterization of the genomic elrD 5'-flanking region. We localized the transcription initiation sites and thus identified two distinct transcripts, elrD1 and elrD2 by 5' RACE PCR. The two transcripts derive from the use of alternative promoters located 915 bp apart. We show that sequences upstream of the elrD1 and elrD2 transcription units can direct expression of the reporter luciferase gene in Xenopus embryos. We also observed length variation of the ELRD first RNA recognition motif (RRM1).