This is a fungal domain of unknown function. This domain can be found in DSC E3 ubiquitin ligase complex subunit 4 (Dsc4) from S. pombe, a component of the DSC E3 ubiquitin ligase complex required for the sre1 transcriptional activator proteolytic cleavage to release the soluble transcription factor from the membrane in low oxygen or sterol conditions. The complex plays also an important role in the multivesicular body (MVB) pathway and functions in a post-endoplasmic reticulum pathway for protein degradation [1]. This domain is also found in GLD1 from S. cerevisiae, also a component of the DSC E3 ubiquitin ligase complex involved in the targeting of the DSC complex to the Golgi apparatus and endosome membranes via the AP3 pathway to ubiquitinate Golgi/endosome membrane proteins [2].

1: Yeast SREBP cleavage activation requires the Golgi Dsc E3 ligase complex. Stewart EV, Nwosu CC, Tong Z, Roguev A, Cummins TD, Kim DU, Hayles J, Park HO, Hoe KL, Powell DW, Krogan NJ, Espenshade PJ; Mol Cell. 2011;42:160-171. PMID:21504829

2: Sorting of a multi-subunit ubiquitin ligase complex in the endolysosome system. Yang X, Arines FM, Zhang W, Li M; Elife. 2018; [Epub ahead of print] PMID:29355480