E3 ubiquitin-protein ligase HECTD3 is an E3 ubiquitin ligase that regulates ubiquitination and degradation of Tara [], MASTL and LKB1 []. HECTD3 interacts with HSP90 and is involved in the HSP90-dependent degradation of CRAF protein []. It has been shown to interact and stabilize MALT1 (mucosa-associated lymphoid tissue 1), and may hence promote cell survival [].
The MASTL kinases carry only a catalytic domain, which contains a long insertion relative to MAST kinases. MASTL, also called greatwall kinase (Gwl), is involved in the regulation of mitotic entry, which is controlled by the coordinated activities of protein kinases and opposing protein phosphatases (PPs) []. The cyclin B/CDK1 complex induces entry into M-phase while PP2A-B55 shows anti-mitotic activity. MASTL/Gwl is activated downstream of cyclin B/CDK1 and indirectly inhibits PP2A-B55 by phosphorylating the small protein alpha-endosulfine (Ensa) or the cAMP-regulated phosphoprotein 19 (Arpp19), resulting in M-phase progression []. Gwl kinase may also play roles in mRNA stabilization and DNA checkpoint recovery [, ]. The human MASTL gene has also been named FLJ14813; a missense mutation in FLJ14813 is associated with autosomal dominant thrombocytopenia [].
