Overview
| Uniprot ID | P60033 |
|---|
| Protein Name | CD81 antigen |
|---|
| Gene Name | CD81 |
|---|
| Organism | Homo sapiens |
|---|
Kla Sites from experimental identification
| Position |
Flanking peptide |
| 124 |
DQIAKDVKQFYDQAL |
Function
Structural component of specialized membrane microdomains known as tetraspanin-enriched microdomains (TERMs), which act as platforms for receptor clustering and signaling. Essential for trafficking and compartmentalization of CD19 receptor on the surface of activated B cells (PubMed:16449649, PubMed:20237408, PubMed:27881302). Upon initial encounter with microbial pathogens, enables the assembly of CD19-CR2/CD21 and B cell receptor (BCR) complexes at signaling TERMs, lowering the threshold dose of antigen required to trigger B cell clonal expansion and antibody production (PubMed:15161911, PubMed:20237408). In T cells, facilitates the localization of CD247/CD3 zeta at antigen-induced synapses with B cells, providing for costimulation and polarization toward T helper type 2 phenotype (PubMed:22307619, PubMed:23858057, PubMed:8766544). Present in MHC class II compartments, may also play a role in antigen presentation (PubMed:8409388, PubMed:8766544). Can act both as positive and negative regulator of homotypic or heterotypic cell-cell fusion processes. Positively regulates sperm-egg fusion and may be involved in acrosome reaction (By similarity). In myoblasts, associates with CD9 and PTGFRN and inhibits myotube fusion during muscle regeneration (By similarity). In macrophages, associates with CD9 and beta-1 and beta-2 integrins, and prevents macrophage fusion into multinucleated giant cells specialized in ingesting complement-opsonized large particles (PubMed:12796480). Also prevents the fusion of mononuclear cell progenitors into osteoclasts in charge of bone resorption (By similarity). May regulate the compartmentalization of enzymatic activities. In T cells, defines the subcellular localization of dNTPase SAMHD1 and permits its degradation by the proteasome, thereby controlling intracellular dNTP levels (PubMed:28871089). Also involved in cell adhesion and motility. Positively regulates integrin-mediated adhesion of macrophages, particularly relevant for the inflammatory response in the lung (By similarity)
Protein Sequence
10
MGVEGCTKCI
20
KYLLFVFNFV
30
FWLAGGVILG
40
VALWLRHDPQ
50
TTNLLYLELG
60
DKPAPNTFYV
70
GIYILIAVGA
80
VMMFVGFLGC
90
YGAIQESQCL
100
LGTFFTCLVI
110
LFACEVAAGI
120
WGFVNKDQIA
130
KDVKQFYDQA
140
LQQAVVDDDA
150
NNAKAVVKTF
160
HETLDCCGSS
170
TLTALTTSVL
180
KNNLCPSGSN
190
IISNLFKEDC
200
HQKIDDLFSG
210
KLYLIGIAAI
220
VVAVIMIFEM
230
ILSMVLCCGI
RNSSVY
Gene Ontology
| Classification |
GO ID |
Description |
| Cellular Component |
GO:0009925 |
basal plasma membrane |
| Cellular Component |
GO:0016323 |
basolateral plasma membrane |
| Cellular Component |
GO:0070062 |
extracellular exosome |
| Cellular Component |
GO:0005925 |
focal adhesion |
| Cellular Component |
GO:0001772 |
immunological synapse |
| Cellular Component |
GO:0016020 |
membrane |
| Cellular Component |
GO:0005886 |
plasma membrane |
| Cellular Component |
GO:0097197 |
tetraspanin-enriched microdomain |
| Cellular Component |
GO:0031982 |
vesicle |
| Molecular Function |
GO:0015485 |
cholesterol binding |
| Molecular Function |
GO:0005178 |
integrin binding |
| Molecular Function |
GO:0042289 |
MHC class II protein binding |
| Molecular Function |
GO:0023026 |
MHC class II protein complex binding |
| Molecular Function |
GO:1990459 |
transferrin receptor binding |
| Molecular Function |
GO:0001618 |
virus receptor activity |
| Biological Process |
GO:0035783 |
CD4-positive, alpha-beta T cell costimulation |
| Biological Process |
GO:0071404 |
cellular response to low-density lipoprotein particle stimulus |
| Biological Process |
GO:0002455 |
humoral immune response mediated by circulating immunoglobulin |
| Biological Process |
GO:0001771 |
immunological synapse formation |
| Biological Process |
GO:0034238 |
macrophage fusion |
| Biological Process |
GO:0014905 |
myoblast fusion involved in skeletal muscle regeneration |
| Biological Process |
GO:0072675 |
osteoclast fusion |
| Biological Process |
GO:1905676 |
positive regulation of adaptive immune memory response |
| Biological Process |
GO:0030890 |
positive regulation of B cell proliferation |
| Biological Process |
GO:0050861 |
positive regulation of B cell receptor signaling pathway |
| Biological Process |
GO:2000563 |
positive regulation of CD4-positive, alpha-beta T cell proliferation |
| Biological Process |
GO:0002863 |
positive regulation of inflammatory response to antigenic stimulus |
| Biological Process |
GO:0043410 |
positive regulation of MAPK cascade |
| Biological Process |
GO:1904352 |
positive regulation of protein catabolic process in the vacuole |
| Biological Process |
GO:0070863 |
positive regulation of protein exit from endoplasmic reticulum |
| Biological Process |
GO:1903911 |
positive regulation of receptor clustering |
| Biological Process |
GO:2001190 |
positive regulation of T cell activation via T cell receptor contact with antigen bound to MHC molecule on antigen presenting cell |
| Biological Process |
GO:0050862 |
positive regulation of T cell receptor signaling pathway |
| Biological Process |
GO:2000553 |
positive regulation of T-helper 2 cell cytokine production |
| Biological Process |
GO:0045944 |
positive regulation of transcription by RNA polymerase II |
| Biological Process |
GO:0061462 |
protein localization to lysosome |
| Biological Process |
GO:0072659 |
protein localization to plasma membrane |
| Biological Process |
GO:0031623 |
receptor internalization |
| Biological Process |
GO:1905521 |
regulation of macrophage migration |
| Biological Process |
GO:0031647 |
regulation of protein stability |
Reference
[1] Shi CM, Wang QC, Li XL, Yang YH, Tang XY et al.. Global Profiling of Protein Lactylation in Human Hippocampi.. Proteomics Clin Appl 19(2):e202400061. 2025 Mar. PMID: 39610256.