Fig. 3 | European Journal of Human Genetics

Fig. 3

From: A novel homozygous ARL13B variant in patients with Joubert syndrome impairs its guanine nucleotide-exchange factor activity

Fig. 3

ARL13B-p.(Gly75Arg) is inactive as a GEF for ARL3, while retain the GTPase activities. a GST-ARL13B, GST-Δ19ARL13B, and GST-Δ19ARL13B-p.(Gly75Arg) were expressed in and purified from HEK cells. Each preparation (2 µg) was analyzed with SDS-PAGE by Coomassie blue (Sigma B0149) staining. Molecular weight standards (Precision Plus; Bio-Rad 161-0373) are shown on the left with indicated sizes. b No differences in intrinsic or GAP-stimulated GTPase activities were detected among GST-RL13B, GST-Δ19ARL13B, and GST-Δ19ARL13B-p.(Gly75Arg). c ARL13B is active as a GEF for ARL3, while ARL13B-p.(Gly75Arg) is inactive. ARL3 (1 µM) was loaded with [3H]GDP prior to use as substrate in the GEF assay, with the 1 µM GST-ARL13B, GST-Δ19ARL13B, or GST-Δ19ARL13B-p.(Gly75Arg) preloaded with 100 µM of GTP. Each analysis was performed in duplicate and repeated at least twice using different ARL13B protein preparations