AP4M1
Adaptor Related Protein Complex 4 Subunit Mu 1
Gene Information Card
| Symbol | AP4M1 |
|---|---|
| Full Name | Adaptor Related Protein Complex 4 Subunit Mu 1 |
| Gene Type | Protein coding |
| Chromosomal Location | 7q22.1 |
| NCBI Gene ID | 9179 ncbi.nlm.nih.gov/gene/9179 |
| Ensembl ID | ENSG00000106331 |
| UniProt ID | O00189 |
| OMIM ID | 602296 |
| HGNC ID | 574 |
| Aliases | MU-4, AP-4, AP4M |
Description
AP4M1 encodes the mu (μ) subunit of the adaptor protein complex 4 (AP-4), a heterotetrameric complex involved in intracellular vesicle trafficking, particularly the sorting of transmembrane proteins from the trans-Golgi network to endosomes and lysosomes. The mu subunit recognizes tyrosine-based sorting signals in the cytoplasmic tails of cargo proteins. Loss-of-function mutations in AP4M1 cause autosomal recessive AP-4 deficiency syndrome, characterized by spastic paraplegia, intellectual disability, and microcephaly.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Hereditary spastic paraplegia 50 (SPG50) | Loss-of-function mutations impair AP-4 complex assembly and cargo sorting, leading to neuronal dysfunction. | OMIM #612936; multiple case reports (PMID: 21194678, 24940034) |
| AP-4 deficiency syndrome | Biallelic mutations disrupt intracellular trafficking, causing developmental delay, spasticity, and seizures. | ClinVar; Orphanet ORPHA:280763 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Brain | 12.5 | Medium |
| Testis | 8.3 | Low |
| Lung | 6.1 | Low |
| Kidney | 5.4 | Low |
| Liver | 3.2 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| SH-SY5Y (neuroblastoma) | 14.2 | Neuronal model |
| HeLa (cervical carcinoma) | 9.8 | Epithelial |
| HEK293 (embryonic kidney) | 7.5 | Common cell line |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1132C>T (p.Arg378*) | Nonsense | Rare | Premature stop; loss of function |
| c.1145delC (p.Pro382Leufs*2) | Frameshift | Rare | Frameshift; loss of function |
| c.1A>G (p.Met1?) | Start loss | Rare | No translation initiation; loss of function |
Mutation functional classification
Loss of Function (LOF)
Most reported AP4M1 mutations are loss-of-function (nonsense, frameshift, splice-site) leading to truncated or absent protein, impairing AP-4 complex function.
Gain of Function (GOF)
No gain-of-function mutations reported.
Dominant Negative (DN)
No dominant-negative mutations reported; disease is autosomal recessive.
View complete mutation data：
Gene Ontology (GO)
Pathways
• AP-4 complex-mediated transport (Reactome: R-HSA-432722)
• Clathrin-mediated endocytosis (KEGG: hsa04144)
Protein Summary
AP4M1 is a 453-amino-acid protein (UniProt O00189) that functions as the mu subunit of the AP-4 complex. It contains a longin domain and a mu homology domain, which mediate cargo recognition and complex assembly. The protein is ubiquitously expressed but enriched in brain. Defects cause hereditary spastic paraplegia type 50.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| AP4M1 Knockout HEK293 Cell Line | EDJ-KQ6486 | Human | 9179 | Details Get a Quote |
| AP4M1 Knockout A-549 Cell Line | EDJ-KQ30607 | Human | 9179 | Details Get a Quote |
| AP4M1 Knockout HCT 116 Cell Line | EDJ-KQ30608 | Human | 9179 | Details Get a Quote |
| AP4M1 Knockout HeLa Cell Line | EDJ-KQ30609 | Human | 9179 | Details Get a Quote |
