3sxl
From Proteopedia
SEX-LETHAL RNA RECOGNITION DOMAINS 1 AND 2 FROM DROSOPHILA MELANOGASTER
Structural highlights
FunctionSXL_DROME Sex determination switch protein which controls sexual development by sex-specific splicing. Regulates dosage compensation in females by suppressing hyperactivation of X-linked genes. Expression of the embryo-specific isoform is under the control of primary sex-determining signal, which depends on the ratio of X chromosomes relative to autosomes (X:A ratio). Expression occurs in 2X:2A cells, but not in X:2A cells. The X:A ratio seems to be signaled by the relative concentration of the X-linked transcription factors SIS-A and SIS-B. As a result, the embryo-specific product is expressed early only in female embryos and specifies female-adult specific splicing; in the male where it is not expressed, the default splicing gives rise to a truncated non-functional protein. The female-specific isoform specifies the splicing of its own transcript, thereby initiating a positive autoregulatory feedback loop leading to female development pathway. The female-specific isoform controls the sex-specific splicing of transformer (TRA); acts as a translational repressor for male-specific lethal-2 (MSL-2) and prevents male-less (MLE), MSL-1 and MSL-3 proteins from associating with the female X chromosome.[1] [2] [3] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedBy binding specific RNA transcripts, the Sex-lethal protein (SXL) governs sexual differentiation and dosage compensation in Drosophila melanogaster. To investigate the basis for RNA binding specificity, we determined the crystal structure of the tandem RNA recognition motifs (RRMs) of SXL. Both RRMs adopt the canonical RRM fold, and the 10-residue, interdomain linker shows significant disorder. In contrast to the previously determined structure of the two-RRM fragment of heterogeneous nuclear ribonucleoprotein Al, SXL displays no interdomain contacts between RRMs. These results suggest that the SXL RRMs are flexibly tethered in solution, and RNA binding restricts the orientation of RRMs. Therefore, the observed specificity for single-stranded, U-rich sequences does not arise from a predefined, rigid architecture of the isolated SXL RRMs. Absence of interdomain contacts in the crystal structure of the RNA recognition motifs of Sex-lethal.,Crowder SM, Kanaar R, Rio DC, Alber T Proc Natl Acad Sci U S A. 1999 Apr 27;96(9):4892-7. PMID:10220389[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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