UEVLD

Model summary

A cytoplasmic, bifunctional enzyme–scaffold that combines an N-terminal ubiquitin E2-variant platform with a C-terminal lactate dehydrogenase-like core. It assembles into oligomers and binds cadherin-associated complexes, positioning it at adhesion and cytoskeletal interfaces while catalyzing NAD(H)-dependent interconversion of pyruvate and lactate. Through this coupling of adhesion scaffolding and redox metabolism, it supports broader metabolic pathways and can be packaged into extracellular vesicles.

Predicted Gene Ontology terms

1. 01

   I begin by dissecting the InterPro architecture and its order along the sequence.

   The N-terminus (residues 1–144) is defined by IPR016135 (Ubiquitin-conjugating enzyme/RWD-like homologous superfamily) and reinforced by IPR008883 (Ubiquitin E2 variant, N-terminal domain, residues 2–145). This tandem strongly indicates an E2-variant scaffold rather than a catalytic ubiquitin-transfer enzyme; E2 variants typically lack the active-site cysteine and instead create protein–protein interaction platforms that regulate ubiquitin-like pathways and cytoskeletal/adhesion assemblies. This architecture predisposes the protein to multivalent binding and oligomerization, which causally supports GO:0042802 identical protein binding and GO:0045296 cadherin binding.

2. 02

   The central and C-terminal halves assemble a classical dehydrogenase core.

   IPR036291 (NAD(P)-binding domain superfamily, residues 172–316) and the paired IPR001236 (Lactate/malate dehydrogenase, N-terminal domain, residues 184–316) together with IPR022383 (Lactate/malate dehydrogenase, C-terminal domain, residues 320–462) create the bipartite fold typical of LDH/MDH enzymes. Multiple family-level signatures—IPR001557 (L-lactate/malate dehydrogenase family, residues 184–208; 290–310; 314–332; 344–335)—confirm this enzymatic identity and span the canonical catalytic core. The C-terminal region is further consolidated by IPR015955 (Lactate dehydrogenase/glycoside hydrolase family 4, C-terminal homologous superfamily, residues 317–471), which stabilizes the oligomeric assembly and substrate-binding groove. This ordered LDH/MDH architecture directly causes GO:0004457 lactate dehydrogenase activity by binding NAD(H) and catalyzing reversible interconversion of pyruvate and lactate.

3. 03

   From molecular function to process, the LDH-like core situates the protein in central carbon metabolism.

   The explicit lactate dehydrogenase activity links to cytosolic redox buffering and pyruvate–lactate cycling. The presence of cadherin-binding and oligomerization tendencies, together with an E2-variant N-terminus, provides a mechanistic bridge to adhesion complexes and cytoskeletal interfaces. This scaffolding role can couple metabolic state to adhesion and signaling hubs. The supplied biological process label, GO:0006570 tyrosine metabolic process, can be rationalized mechanistically: adhesion/cytoskeletal assemblies and redox enzymes often intersect with tyrosine pathway enzymes and tyrosine phosphorylation cascades; by organizing cadherin-associated complexes and tuning NAD(H) pools, the protein can modulate flux and signaling in tyrosine-related metabolism.

4. 04

   Cellular localization follows from the soluble, enzyme-rich architecture and adhesion coupling.

   The absence of transmembrane segments and the soluble dehydrogenase fold argue for a cytoplasmic residency, consistent with a cytosolic metabolic scaffold. The GO cellular component leaf GO:0070062 extracellular exosome can be reconciled by noting that many cytosolic metabolic/scaffold proteins are selectively packaged into exosomes; cadherin-associated assemblies and oligomeric LDH-like complexes are frequently detected in extracellular vesicles.

5. 05

   Integrating these lines of evidence yields a mechanistic hypothesis: an N-terminal E2-variant platform nucleates oligomerization and cadherin/cytoskeleton interactions, while the central–C-terminal LDH-like core provides NAD(H)-dependent catalytic and binding activities.

   This dual architecture causes a bifunctional behavior—metabolic enzyme activity coupled to adhesion/scaffold functions—positioned in the cytoplasm and trafficked via exosomes. Likely interaction partners include cadherins and catenins at adhesion sites, actin-associated adaptors, and ubiquitin-like pathway regulators; oligomerization with itself (identical protein binding) stabilizes higher-order assemblies that tune lactate/pyruvate balance and interface with tyrosine-related metabolic signaling.