High impact information on Hrb27C

• We identify the 50-kD protein as hrp48, a protein similar to the mammalian splicing factor hnRNP A1, and show that hrp48 recognizes specific nucleotides in a pseudo-5' splice site within the inhibitory element [1].
• The results indicate that PSI is an alternative splicing factor that regulates tissue-specific splicing, probably through interactions with generally expressed factors such as hrp48 [1].
• Previous biochemical studies have implicated hrp48 as a component of a ribonucleoprotein complex involved in the regulation of the tissue-specific alternative splicing of the P-element third intron (IVS3) [2].
• Using a P-element third-intron reporter transgene, we found that reduced levels of hrp48 partially relieve IVS3 splicing inhibition in somatic cells [2].
• Mutations in the hrp48 gene were identified and characterized. hrp48 is an essential gene [2].

Biological context of Hrb27C

• Our analyses support dual cooperative roles for Sqd, Hrb27C and Otu during Drosophila oogenesis [3].
• Dxl6 is located on the second chromosome in a position next to hrp48 and Dwee1 [4].

Anatomical context of Hrb27C

• Analysis of three hrp48 mutant alleles reveals that Hrp48 levels are crucial for polarization of the oocyte during mid-oogenesis [5].

Regulatory relationships of Hrb27C

• Our data demonstrate a novel role for Hrb27C in promoting grk localization [3].

Other interactions of Hrb27C

• We show that Sqd interacts with Hrb27C, an hnRNP previously implicated in splicing [3].
• The hrp48 alleles cause a different oskar mRNA localization defect from other mutants, and disrupt the formation of GFP-Staufen particles [6].

1. Regulation of tissue-specific P-element pre-mRNA splicing requires the RNA-binding protein PSI. Siebel, C.W., Kanaar, R., Rio, D.C. Genes Dev. (1994)
2. Mutations in the hrp48 gene, which encodes a Drosophila heterogeneous nuclear ribonucleoprotein particle protein, cause lethality and developmental defects and affect P-element third-intron splicing in vivo. Hammond, L.E., Rudner, D.Z., Kanaar, R., Rio, D.C. Mol. Cell. Biol. (1997)
3. Hrb27C, Sqd and Otu cooperatively regulate gurken RNA localization and mediate nurse cell chromosome dispersion in Drosophila oogenesis. Goodrich, J.S., Clouse, K.N., Schüpbach, T. Development (2004)
4. Localized expression of the Drosophila gene Dxl6, a novel member of the serine/arginine rich (SR) family of splicing factors. Vorbrüggen, G., Onel, S., Jäckle, H. Mech. Dev. (2000)
5. Hrp48, a Drosophila hnRNPA/B homolog, binds and regulates translation of oskar mRNA. Yano, T., López de Quinto, S., Matsui, Y., Shevchenko, A., Shevchenko, A., Ephrussi, A. Dev. Cell (2004)
6. The Drosophila hnRNPA/B homolog, Hrp48, is specifically required for a distinct step in osk mRNA localization. Huynh, J.R., Munro, T.P., Smith-Litière, K., Lepesant, J.A., St Johnston, D. Dev. Cell (2004)