orb encodes female- and male-specific protein products containing two putative RNA-binding domains. Lantz et al(1992) .It is localized in a subcortical network within the oocyte. orb may be involved in the regulation of translation. orb functions in both early and late grk-Egfr signaling pathways, and in each case is required for the localized expression of grk protein.orb is also required for osk protein expression in oocytes. orb protein autoregulates its own expression through sequences in the 3'UTR of the orb mRNA. 280bp sequence from the orb 3' untranslated region is capable of reproducing orb mRNA complex localization pattern during oogenesis. Multiple cis-acting elements appear to be required for proper targeting of orb mRNA. Lantz and Schedl, (1994) .
Mutant analysis suggests that orb is required for A/P axis formation and D/V patterning. Christerson and McKearin (1994) .
All of the cells in the female germline cyst form synaptonemal complex in orb mutants. Huynh and St. Johnston (2000) .
General function
Cytoskeleton, RNA processing, RNA binding
Comment
RNA binding protein-like.
Uridine-rich cytoplasmic polyadenylation element Regulation of translation
Cellular localization
Cytoplasmic
Comment
Ovarian function
Oogenesis, cyst formation
Comment
orb is required for the localized expression of grk and oskar proteins.
Expression regulated by
Comment
Ovarian localization
Oocyte, nurse cell,pole cell
Comment
Follicle stages
oogenesis, cyst
Comment
Phenotypes
Mutations
1 mutations
Species: D. melanogaster
Mutation name: orb-dec
type: None fertility: infertile - ovarian defect Comment: female-sterile ovaries tumorous: Oogenesis has blocked during a stage of cyst development, the ovaries are very small and consist of germarium like structures populated by many small undifferentiated cells. Lantz et al (1994) . Disrupts cyst formation near the time that the 16 cell cluster is formed and causes cyst degeneration. Ovaries are tiny, each ovariole consists of a germarium-like region and occasionally one or two egg chambers, egg chambers are often empty. Aberrant cellular morphology is seen in the germarial mid region, blebs appear on the surface of cystocytes (blebs are presumed to be the evidence of degenerating cells and cellular debris). orbdec interacts genetically with Egfr and grk, double heterozygote embryos display fused dorsal appendages Christerson and McKearin (1994) .