Encapsulated into the Cvt vesicle that fuses with the vacuole. Exposure to the acidic pH of the vacuolar lumen results in disassembly of the preApe1 complex to preApe1 dodecamers.131 Finally, PrB cleaves the N-terminal propeptide in preApe1 to produce the active 50 kDa enzyme.132,133 ApeI is also known as Lap4 because it was initially characterized as a Leu aminopeptidase in a screen for yeast mutants defective for the ability to hydrolyze the synthetic substrate Leu -naphthylamide.108 Ape1 was also shown to mediate resistance to Cd 2+, which is otherwise toxic and induces oxidative stress.134 Yeast sequester Cd 2+ in the vacuole as a glutathione (GSH) S-conjugate. The GSH is recycled from the vacuole by the action of gamma-glutamyltranspeptidase (Ecm38), which hydrolyzes Glu, leaving a Cys-Gly dipeptide, which is thought to be furtherwww.landesbioscienceCellular Logisticse28023-014 Landes Bioscience. Do not distributeFigure 2. (A) Sequence alignment of Ape3 (MeROPS accession: MeR001288) and Pff1 (MeROPS accession: MeR001911), two vacuole-resident yeast metalloproteases. A global sequence alignment was performed using Clustalw default parameters.142 Only the M28 domains of Ape3 and Ybr074 are shown according to the MeROPS defined protease domain boundaries. (B) Active site of the M28 metalloprotease, AM-1 Aminopeptidase, from Aneurinibacillus sp. strain AM-1 (MeROPS accession: MeR100667; protease domain: Gly173-Arg436). Of the M28 metalloproteases whose crystal structures have been solved, the protease domain amino acid sequence of AM-1 Aminopeptidase is most similar to that of the yeast Pff1 (MeROPS accession: MeR001911; protease domain: Asn96-Ala341).Encorafenib The MeROPS defined protease domain boundaries of AM-1 and Pff1 show 19.Fremanezumab 2 identity when compared by global sequence alignment using Clustalw default parameters.PMID:23357584 142 Catalytic residues are labeled in blue and metal coordinating residues are labeled in red in both this panel and in part (A). Zinc ions are depicted as red spheres. This image was captured from PDB iD: 2eK9 using 3D Molecule viewer of vector NTi Advance, version 11.5.2 (Life Technologies).degraded by Ape1.134 Thus, Ape1 is required for GSH homeostasis, and defects in this process lead to Cd 2+ sensitivity. However, more recent work has identified an alternative GSH degradation pathway involving the cytosolic dipeptidase Dug1, which is a member of the M20 family of metalloproteases. This study demonstrated that Ape1 was not required for growth of a met15 strain on media in which GSH was the only source of sulfur.135 Aminopeptidase Y (Ape3), encoded by the gene APE3, is a metallo-aminopeptidase of the same M28 family of proteases asthe recently discovered, putative vacuolar protease, Ybr074w (see below). Like YBR074w, the APE3 locus is found on chromosome II. Global pairwise sequence alignment of Ape3 and Ybr074w, shown in Figure 2, reveals 5.7 amino acid sequence identity, while comparison of the M28 protease domains indicates 22 sequence identity including conservation of catalytic residues.136 Ape3 is synthesized as a 60 kDa precursor bearing a 21 amino acid signal sequence directing its translocation into the ER.137 The signal sequence is cleaved in the ER, and the Ape3 precursore28023-Cellular Logisticsvolume014 Landes Bioscience. Do not distributeis targeted to the Golgi, where–as evident with several of the other enzymes discussed above–it is recognized by Vps10 for vacuole targeting.115 Also similar to some of the.