MTX1 (metaxin-1) is a non-enzymatic mitochondrial outer membrane metaxin-family accessory subunit of the mammalian SAM complex. Its best-supported core role is structural support of SAM-mediated insertion and assembly of beta-barrel outer membrane proteins such as VDACs and TOM40, with additional non-core links to MIB/MICOS-associated organization and mitochondrial quality control.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0045040 protein insertion into mitochondrial outer membrane | IBA GO_REF:0000033 | ACCEPT | Summary: Correct phylogenetic inference. MTX1 is an accessory SAM subunit involved in SAM-mediated insertion/assembly of beta-barrel proteins into the mitochondrial outer membrane. Supporting Evidence: file:human/MTX1/MTX1-deep-research-falcon.md MTX1 is best supported as an **accessory subunit of the mitochondrial Sorting and Assembly Machinery (SAM)** required for efficient **import/assembly of Ξ²-barrel proteins** into the OMM |
| GO:0070096 mitochondrial outer membrane translocase complex assembly | IBA GO_REF:0000033 | ACCEPT | Summary: Accepted as a SAM-related assembly role. MTX1 supports assembly of beta-barrel outer membrane proteins, including TOM complex components such as TOM40, rather than acting as a catalytic enzyme. |
| GO:0001401 SAM complex | IBA GO_REF:0000033 | ACCEPT | Summary: Correct. MTX1 is a metaxin-family accessory subunit of the mammalian SAM complex with SAMM50, MTX2, and MTX3. |
| GO:0001401 SAM complex | IEA GO_REF:0000002 | ACCEPT | Summary: Correct InterPro-derived complex annotation. The Falcon review identifies MTX1 as a mammalian SAM complex accessory subunit. |
| GO:0005741 mitochondrial outer membrane | IEA GO_REF:0000044 | ACCEPT | Summary: Correct UniProt-derived localization. MTX1 is an outer mitochondrial membrane SAM/metaxin protein. |
| GO:0016020 membrane | IEA GO_REF:0000044 | MARK AS OVER ANNOTATED | Summary: Correct but overly general. MTX1 is specifically localized to the mitochondrial outer membrane and SAM complex. Reason: Subsumed by mitochondrial outer membrane and SAM complex annotations. |
| GO:0007595 lactation | IEA GO_REF:0000107 | REMOVE | Summary: This automatic orthology transfer does not match the synthesized function of human MTX1 as a mitochondrial SAM accessory factor. Falcon research did not identify MTX1-specific evidence for lactation as a gene-level core process. Reason: Unsupported organism-level phenotype transfer; not part of the curated MTX1 mitochondrial SAM function. |
| GO:0001401 SAM complex | IPI PMID:17510655 Conserved roles of Sam50 and metaxins in VDAC biogenesis. | ACCEPT | Summary: Accepted. Conserved roles of metaxins and Sam50 in VDAC biogenesis support MTX1 membership in the SAM complex. |
| GO:0005741 mitochondrial outer membrane | NAS PMID:31387448 Mitochondria-hubs for regulating cellular biochemistry: emer... | ACCEPT | Summary: Accepted. MTX1 is consistently described as a mitochondrial outer membrane metaxin/SAM component. |
| GO:0045040 protein insertion into mitochondrial outer membrane | NAS PMID:31387448 Mitochondria-hubs for regulating cellular biochemistry: emer... | ACCEPT | Summary: Accepted as the core MTX1 process. MTX1 acts as a non-catalytic accessory factor for SAM-mediated insertion/assembly of beta-barrel proteins into the mitochondrial outer membrane. |
| GO:0005739 mitochondrion | HTP PMID:34800366 Quantitative high-confidence human mitochondrial proteome an... | MARK AS OVER ANNOTATED | Summary: Correct but too general. MTX1 is specifically localized to the mitochondrial outer membrane and SAM complex. Reason: Subsumed by mitochondrial outer membrane and SAM complex annotations. |
| GO:0005515 protein binding | IPI PMID:31644573 Armadillo repeat-containing protein 1 is a dual localization... | REMOVE | Summary: Protein binding is too generic to represent MTX1 function. The relevant biology is membership in SAM and non-core association with MIB/MICOS-linked assemblies. Reason: Generic protein binding is uninformative; complex membership and mitochondrial assembly terms capture the supported function. |
| GO:0001401 SAM complex | HDA PMID:26477565 Evolution and structural organization of the mitochondrial c... | ACCEPT | Summary: Accepted. Affinity/proteomics evidence supports MTX1 in SAM-containing mitochondrial outer membrane assemblies. |
| GO:0007007 inner mitochondrial membrane organization | IC PMID:26477565 Evolution and structural organization of the mitochondrial c... | KEEP AS NON CORE | Summary: Plausible secondary consequence of MTX1 association with MIB/MICOS-linked assemblies, but not the primary curated function compared with SAM-mediated outer membrane beta-barrel biogenesis. Reason: MIB/MICOS-associated architecture is supported as an additional role, not the core MTX1 function. |
| GO:0140275 MIB complex | HDA PMID:26477565 Evolution and structural organization of the mitochondrial c... | KEEP AS NON CORE | Summary: Supported as an additional MTX1-associated complex context. Keep as non-core because the strongest synthesized function is SAM-mediated beta-barrel outer membrane protein biogenesis. Reason: MIB/MICOS association is secondary to the core SAM complex role. |
| GO:0016020 membrane | TAS PMID:8660965 Structure and organization of the human metaxin gene (MTX) a... | MARK AS OVER ANNOTATED | Summary: Correct but too general. MTX1 is specifically a mitochondrial outer membrane metaxin/SAM protein. Reason: Subsumed by mitochondrial outer membrane and SAM complex annotations. |
Loading supporting contentβ¦
Download this section (compressed HTML)Q: Which human MTX1 surfaces are required for SAM-mediated VDAC/TOM40 beta-barrel assembly versus MIB/MICOS-associated interactions?
Q: Is MTX1 turnover by LC3C/p62-linked piecemeal mitophagy regulated by the same interfaces used for SAM complex assembly?
Experiment: Use endogenous MTX1 knockout/rescue with domain or interface mutants, then assay SAM complex assembly, VDAC1/TOM40 import and assembly, mitochondrial ultrastructure, and LC3C/p62-dependent MTX1 turnover.
Hypothesis: MTX1 contributes separable interfaces for SAM beta-barrel assembly and MIB/MICOS-associated mitochondrial architecture.
Type: endogenous rescue, import assay, and mitochondrial proteomics
Loading supporting contentβ¦
Download this section (compressed HTML)Loading supporting contentβ¦
Download this section (compressed HTML)