MID1, mutated in Opitz syndrome, encodes an ubiquitin ligase that targets phosphatase 2A for degradation. |
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Authors: | A Trockenbacher V Suckow J Foerster J Winter S Krauss H H Ropers R Schneider S Schweiger |
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Institution: | Institute of Biochemistry, Peter-Mayr-Strasse 1a, 6020 Innsbruck, Austria. |
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Abstract: | The gene MID1, the mutation of which causes X-linked Opitz G/BBB syndrome (OS, MIM 300000), encodes a microtubule-associated protein (MAP). We show that mutation of MID1 leads to a marked accumulation of the catalytic subunit of protein phosphatase 2A (PP2Ac), a central cellular regulator. PP2Ac accumulation is caused by an impairment of a newly identified E3 ubiquitin ligase activity of the MID1 protein that normally targets PP2Ac for degradation through binding to its alpha4 regulatory subunit in an embryonic fibroblast line derived from a fetus with OS. Elevated PP2Ac causes hypophosphorylation of MAPs, a pathological mechanism that is consistent with the OS phenotype. |
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