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| | Genomic organization (A) and transcript variants (B) of ARHGAP20.
(A) Gene structure (drawn to scale): black boxes represent exons.
(B) Transcripts (drawn to scale): boxes, exons; UTR, untranslated region; light shaded box, coding region; shaded and dark shaded boxes, nucleotide sequences coding for protein domains (PH: pleckstrin homology domain, RA: ras association domain; RhoGAP: RhoGAP domain). |
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| Description | 19 exons spanning 136.1 kb genomic DNA. |
| Transcription | 5.9-6.2 kb mRNA, coding sequence: 3.5-3.6 kb
Alternative splicing of the first 5 exons results in the expression of 5 transcript variants (ARHGAP20-1e, ARHGAP20-1d, ARHGAP20-1ad, ARHGAP20-1be, ARHGAP20-1c). |
| Pseudogene | None. |
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| | Schematic representation of ARHGAP20 protein variants as deduced from the transcripts. Hatched box, amino-terminal extension of unknown function; PH: pleckstrin homology domain, RA: ras association domain; RhoGAP: RhoGAP domain. |
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| Description | The amino-terminal region shows significant homology to a pleckstrin homology (PH) domain commonly found in eukaryotic signaling proteins. Adjacent to the PH domain a Ras association (RA) domain is postulated, which is found in proteins involved in GTPase-mediated signaling processes. The central section of the protein contains a RhoGAP domain, which is crucial for the regulation of Rho-like GTPases by Rho GTPase-activating proteins in the course of transmitting diverse intracellular signals. |
| Expression | Predominantly expressed in brain, but transcripts were also detected in peripheral blood lymphocytes. |
| Localisation | Cytoplasm |
| Function | The presence of a RhoGAP domain in combination with PH and RA modules indicates that ARHGAP20 is involved in the regulation of Rho-family GTPases. ARHGAP20 was shown to be activated by Rap1 and to induce inactivation of Rho, resulting in the neurite outgrowth. |
| Homology | Mouse: RarhoGAP (RhoGAP having the RA domain), Arhgap20.
Rat: RahoGAP (RhoGAP having the RA domain), Arhgap20. |
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