High impact information on MATALPHA2

• A conserved ubiquitin ligase of the nuclear envelope/endoplasmic reticulum that functions in both ER-associated and Matalpha2 repressor degradation [1].
• Here we identify Doa10/Ssm4 as a yeast E3 that is embedded in the endoplasmic reticulum (ER)/nuclear envelope yet can target the soluble transcription factor Matalpha2 [1].
• RE activity is repressed in MATalpha cells by binding of the Matalpha2-Mcm1 corepressor to a site within the RE [2].
• Mutation of the two Matalpha2 binding sites removes most, but not all, of this repression, and RE chromatin structure in MATalpha cells becomes indistinguishable from that seen in MATa [2].
• Further, a mutation that alters the ability of Mcm1 to act with Matalpha2 in repressing a-specific genes also alters donor preference in either mating type [2].

Biological context of MATALPHA2

• Matalpha2p cooperates with Tup1p to block both chromatin remodeling and Mcm1p-associated activation [3].
• Point mutations in Tup1 that specifically affect the Tup1-Matalpha2 interaction cluster on one surface of the propeller [4].
• Furthermore, nuclear import functions are crucial for both Deg1-induced degradation as well as for the turnover of the endogenous Matalpha2 protein [5].
• The Matalpha2-Mcm1 complex, which normally represses a-specific genes, is defective in rst- diploids because Matalpha2 is destabilized in rst- diploids, possibly as a consequence of its relocalization from the nucleus to the cytoplasm [6].

Other interactions of MATALPHA2

• Autocrine activation of the pheromone response pathway in matalpha2- cells is attenuated by SST2- and ASG7-dependent mechanisms [7].
• The short-lived Matalpha2 transcriptional repressor is protected from degradation in vivo by interactions with its corepressors Tup1 and Ssn6 [8].

References