Developmental expression of Drosophila RNP-4F, a fly homologue of the human P110/Sart3 protein and U4/U6 snRNP recycling factor

Drosophila rnp-4f is a single-copy gene which was the first reported example of a gene in Drosophila to display RNA editing of its transcripts. It is predicted that RNP-4F proteins 943 and 639 amino acids long arise from two non-edited cDNAs that undergo alternative splicing. These isoforms exhibit ∼22% sequence identity and ∼40% sequence similarity to other family members. The 943aa RNP-4F protein has one RRM, 3 HAT domains common to known RNA binding proteins, and the 12aa highly conserved LSM motif at the extreme C-terminus. Drosophila RNP-4F is a homologue of human P110/Sart3 and Prp24 which function as U4/U6 di-snRNP recycling factors. The exact function of RNP-4F is unknown but may play a role in RNA splicing in Drosophila. Western blot analysis reveals a complex temporal pattern of RNP-4F proteins developmentally regulated. Consistent with RNA localization data, immunostaining shows a uniform distribution of RNP-4F in most cells and tissues.