MUTATIONS IN THE HRP48 GENE, WHICH ENCODES A DROSOPHILA HETEROGENEOUSNUCLEAR RIBONUCLEOPROTEIN PARTICLE PROTEIN, CAUSE LETHALITY AND DEVELOPMENTAL DEFECTS AND AFFECT P-ELEMENT 3RD-INTRON SPLICING IN-VIVO

The Drosophila melanogaster hnRNP protein, hrp48, is an abundant heter ogeneous nuclear RNA-associated protein. Previous biochemical studies have implicated hrp48 as a component of a ribonucleoprotein complex in volved in the regulation of the tissue-specific alternative splicing o f the P-element third intron (IVS3). We have taken a genetic approach to analyzing the role of hrp48. Mutations in the hrp48 gene were ident ified and characterized, hrp48 is an essential gene, Hypomorphic mutat ions which reduce the level of hrp48 protein display developmental def ects, including reduced numbers of ommatidia ins the eye and morpholog ical bristle abnormalities, Using a P-element third-intron reporter tr ansgene, we found that reduced Bevels of hrp48 partially relieve IVS3 splicing inhibition in somatic cells, This is the first direct evidenc e that hrp48 plays a functional role in IVS3 splicing inhibition.