| Biological process / pathway | Specific role of MVB12B / ESCRT-I | Key evidence / mechanistic note | Citations |
|---|---|---|---|
| Multivesicular body (MVB) biogenesis and intraluminal vesicle (ILV) formation | MVB12B is a fourth subunit of human ESCRT-I, which acts upstream of ESCRT-II/III during endosomal cargo sorting and ILV formation in MVBs. | Human ESCRT-I is a 1:1:1:1 heterotetramer containing TSG101, VPS28, VPS37 and an MVB12-family subunit; ESCRT-I is recruited to endosomal membranes and helps organize downstream ESCRT assembly for reverse-topology membrane budding. | (pqac-00000000, pqac-00000001, pqac-00000003, pqac-00000007) |
| Exosome biogenesis and secretion | Through its role in ESCRT-I, MVB12B contributes to formation of ILVs within MVBs that can later be secreted as exosomes when MVBs fuse with the plasma membrane. | Reviews of ESCRT-dependent exosome biogenesis place ESCRT-I as a core organizer of ILV generation and exosome production; MVB12-family proteins are part of this machinery in metazoans. | (pqac-00000003, pqac-00000011) |
| Viral budding and egress (HIV-1) | MVB12B supports ESCRT-I function in HIV-1 budding; perturbing MVB12 proteins disrupts virion release and causes abnormal viral assembly and Gag processing. | Foundational work identified human MVB12 proteins as ESCRT-I subunits required for efficient HIV budding, linking MVB12B directly to viral membrane scission. | (pqac-00000001, pqac-00000007) |
| Viral budding and egress (broader ESCRT-dependent viruses) | MVB12B is inferred to contribute when viruses hijack ESCRT-I for budding or egress, because ESCRT-I is a recurrent viral cofactor across enveloped viruses. | Recent reviews emphasize ESCRT-I as a host module used in enveloped virus release; MVB12-family subunits are part of the human ESCRT-I complex that can be co-opted in these contexts. | (pqac-00000000, pqac-00000003) |
| Innate immune signaling (STING-TBK1-MVB12B axis) | MVB12B is phosphorylated downstream of STING-TBK1 signaling and mediates extracellular-vesicle-based paracrine immune communication. | During intracellular bacterial infection, TBK1-dependent phosphorylation of MVB12B is required for packaging immunostimulatory DNA into extracellular vesicles, enabling bystander cGAS-STING activation. | (pqac-00000002, pqac-00000008) |
| DNA sorting into extracellular vesicles | MVB12B has a specialized cargo-selection role in sorting DNA into EVs/exosomes, beyond a purely structural ESCRT-I function. | Mvb12b knockout or mutation of the TBK1-regulated phosphorylation site impairs EV-mediated DNA transfer and downstream IFN induction in recipient cells. | (pqac-00000002, pqac-00000008) |
| Cytokinesis and abscission | MVB12B is not individually singled out in the cited cytokinesis reviews, but as an ESCRT-I subunit it is part of the upstream ESCRT-I module that helps recruit/organize downstream ESCRT-III during abscission. | ESCRT-I is positioned at the top of the abscission pathway, where TSG101 and associated ESCRT-I proteins help nucleate ESCRT-II/III assembly at the midbody. | (pqac-00000003, pqac-00000009, pqac-00000010) |
| Autophagy and lysosomal trafficking | MVB12B likely participates in ESCRT-I-dependent membrane remodeling steps linked to autophagosome closure, endolysosomal trafficking, and cargo delivery to lysosomes. | ESCRT reviews describe ESCRT-I as part of the upstream machinery in autophagy-related and lysosomal trafficking pathways, although the evidence is generally at complex level rather than MVB12B-specific. | (pqac-00000000, pqac-00000003, pqac-00000011) |
| Membrane repair | MVB12B is plausibly involved as an ESCRT-I component in membrane repair pathways that depend on coordinated ESCRT recruitment and remodeling. | Reviews describe ESCRT machinery in membrane sealing/repair; the clearest direct mechanistic assignments are often to ESCRT-III/VPS4, with ESCRT-I acting upstream in recruitment/scaffolding. | (pqac-00000003, pqac-00000009, pqac-00000010) |


*Table: This table summarizes the main biological processes linked to human MVB12B as an ESCRT-I subunit, highlighting where evidence is direct for MVB12B versus inferred from ESCRT-I complex biology. It is useful for separating well-supported specialized roles, such as TBK1-dependent DNA sorting into EVs, from broader complex-level functions like cytokinesis and membrane repair.*