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Description

Ran GTPase-activating protein (UniProt: Q9VIW3, also known as RanGAP, Protein segregation distorter) is encoded by the RanGAP (also known as Sd, CG9999) gene (Gene ID: 35223) in Drosophila melanogaster. Ran is a small GTPase located predominantly in the nucleus. Along with its cofactors, RanGAP and RanGEF (Ran guanine nucleotide exchange factor), Ran is required for nuclear transport, cell cycle regulation, mitotic spindle formation, and post-mitotic nuclear envelope assembly. RanGAP is a GTPase activator for the nuclear Ras-related regulatory protein Ran and converts it to the putatively inactive GDP-bound state. It has been shown that the cytoplasmic localization of RanGAP and the nuclear localization of RanGEF are important in establishing a concentration gradient of RanGTP across the nuclear envelope that is needed for proper functioning of the Ran signaling pathway. In Drosophila, Sd, a dominant neomorphic mutation, encodes a truncated form of RanGAP that lacks 234 amino acids at the C- terminus and acts as a trans-acting factor that is essential for meiotic distortion. This distortion is observed in flies that carry the RanGAP tandem duplication and express a RanGAP truncated protein. Both full length and truncated forms of RanGAP are expressed in Drosophila testis and the truncated form also displays enzymatic activity. (Ref.: Kusano A et al. (2002). Proc. Natl. Acad. Sci. USA 99(10): 6866-6870).