LAPTM4B
Lysosomal-associated transmembrane protein 4B
Also known as: LAP4B_HUMAN, LC27
Cross-references: UniProt · Ensembl · Human Protein Atlas · GeneCards · NCBI Gene
Protein identityUniProt · HPA
- UniProt accession
- Q86VI4
- Gene
- LAPTM4B
- Ensembl
- ENSG00000104341
- Chromosome
- 8
- Canonical length
- 317 aa
- Protein class
- Predicted membrane proteins, Transporters
- Subcellular location
- Golgi apparatus
- Quaternary structure
- Homooligomer
OverviewNCBI Gene
Enables ceramide binding activity; enzyme binding activity; and phosphatidylinositol bisphosphate binding activity. Involved in several processes, including endosome transport via multivesicular body sorting pathway; negative regulation of macromolecule metabolic process; and regulation of lysosomal membrane permeability. Located in several cellular components, including endosome; lysosomal membrane; and plasma membrane. [provided by Alliance of Genome Resources, Jul 2025]
Canonical amino-acid sequenceUniProt
317 residues, UniProt reviewed canonical sequence.
>Q86VI4|LAPTM4B
1 MTSRTRVTWP SPPRPLPVPA AAAVAFGAKG TDPAEARSSR GIEEAGPRAH GRAGREPERR
61 RSRQQRRGGL QARRSTLLKT CARARATAPG AMKMVAPWTR FYSNSCCLCC HVRTGTILLG
121 VWYLIINAVV LLILLSALAD PDQYNFSSSE LGGDFEFMDD ANMCIAIAIS LLMILICAMA
181 TYGAYKQRAA WIIPFFCYQI FDFALNMLVA ITVLIYPNSI QEYIRQLPPN FPYRDDVMSV
241 NPTCLVLIIL LFISIILTFK GYLISCVWNC YRYINGRNSS DVLVYVTSND TTVLLPPYDD
301 ATVNGAAKEP PPPYVSALocalizationUniProt · AlphaFold · HPA
Whether an antibody against LAPTM4B can act on the native protein depends on physical access: surface and secreted proteins are reachable by circulating antibodies, intracellular proteins usually are not.
- Antibody reachability
- Cell surface
- Secreted
- No
- Transmembrane segments
- 4
- Mean surface accessibility (rSASA)
- 0.5
- Highest tissue expression
- 352 nTPM
Expression across tissuesHPA
Tissue
- retina: 352 nTPM
- heart muscle: 207 nTPM
- parathyroid gland: 174 nTPM
- choroid plexus: 161 nTPM
- skeletal muscle: 144 nTPM
- tongue: 109 nTPM
Single-cell type
- rod photoreceptor cells: 641 nCPM
- cone photoreceptor cells: 472 nCPM
- gastric progenitor cells: 336 nCPM
- hematopoietic stem cells: 306 nCPM
- platelets: 275 nCPM
- myonuclei: 246 nCPM
Immune cell
- basophil: 3.3 nTPM
- MAIT T-cell: 1.4 nTPM
- naive CD8 T-cell: 0.9 nTPM
- naive CD4 T-cell: 0.8 nTPM
- gdT-cell: 0.5 nTPM
- memory CD4 T-cell: 0.4 nTPM
Brain region
- choroid plexus: 147 nTPM
- white matter: 85 nTPM
- spinal cord: 78 nTPM
- thalamus: 77 nTPM
- medulla oblongata: 71 nTPM
- pons: 65 nTPM
Genetic constraint and essentialitygnomAD · DepMap
Does the body need this protein intact? Low LOEUF or a strong DepMap dependency means loss or blockade of the protein is likely to be felt.
- gnomAD LOEUF (loss-of-function intolerance)
- 1.8
- gnomAD pLI
- 0
- gnomAD missense Z
- -0.11
- DepMap mean gene effect
- 0.04
- DepMap dependency class
- selective
Cancer expressionTCGA
Across TCGA tumor cohorts, this protein is over-expressed in roughly 14% of surveyed tumor types (aggregate summary; per-cohort expression, alteration, and survival load in the interactive view).
OntologyGO
Biological processes
- endosome organization
- endosome transport via multivesicular body sorting pathway
- negative regulation of lysosomal protein catabolic process
- negative regulation of transforming growth factor beta1 production
- regulation of lysosome organization
- regulation of lysosomal membrane permeability
Molecular functions
- ceramide binding
- kinase binding
- phosphatidylinositol bisphosphate binding
- ubiquitin protein ligase binding
Cellular components
Protein domainsUniProt · Pfam · InterPro
KeywordsUniProt
InteractionsUniProt · HPA
Protein binding partners of LAPTM4B in the human serome: UniProt-annotated complex subunits plus reported interactors. Each links to its own Seroatlas record.
Antibody and autoantibody relevanceSeroatlas analysis
Seroatlas reads LAPTM4B as an antibody target. Whether an autoantibody or antibody against LAPTM4B could matter depends on whether native LAPTM4B is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.
LAPTM4B is annotated at the cell surface, where native LAPTM4B is exposed to circulating antibodies and is a prime autoantibody target that could block, deplete, or overstimulate it.
Annotation status
The present source text does not explicitly label LAPTM4B as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.
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