Kuan-Yu Chen, Pei-Chin Tsai, Ya-Wen Liu, Fang-Jen S Lee
Institute of Molecular Medicine, College of Medicine, National Taiwan University and Department of Medical Research, National Taiwan University Hospital, Taipei 100, Taiwan.
Journal of cell science 2012 Oct 1Golgins play diverse roles in regulating the structure and function of the Golgi. The yeast golgin Imh1p is targeted to the trans-Golgi network (TGN) through interaction of its GRIP domain with GTP-bound Arl1p. Recycling of Arl1p and Imh1p to the cytosol requires the hydrolysis of GTP bound to Arl1p; however, the point at which GTP hydrolysis occurs remains unknown. Here, we report that self-interaction of Imh1p plays a role in modulating spatial inactivation of Arl1p. Deletion of IMH1 in yeast decreases the amount of the GTP-bound Arl1p and results in less Arl1p residing on the TGN. Biochemically, purified Imh1p competes with Gcs1p, an Arl1p GTPase-activating protein (GAP), for binding to Arl1p, thus interfering with the GAP activity of Gcs1p toward Arl1p. Furthermore, we demonstrate that the self-interaction of Imh1p attenuates the Gcs1p-dependent GTP hydrolysis of Arl1p. Thus, we propose that the golgin Imh1p serves as a feedback regulator to modulate the GTP hydrolysis of Arl1p.
Kuan-Yu Chen, Pei-Chin Tsai, Ya-Wen Liu, Fang-Jen S Lee. Competition between the golgin Imh1p and the GAP Gcs1p stabilizes activated Arl1p at the late-Golgi. Journal of cell science. 2012 Oct 1;125(Pt 19):4586-96
PMID: 22767516
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