Protein: LPQH_MYCTU
Sequence: MKRGLTVAVAGAAILVAGLSGCSSNKSTTGSGETTTAAGTTASPGAASGPKVVIDGKDQNVTGSVVCTTAAGNVNIAIGGAATGIAAVLTDGNPPEVKSVGLGNVNGVTLGYTSGTGQGNASATKDGSHYKITGTATGVDMANPMSPVNKSFEIEVTCS
What is the function of this protein?
A host TLR2 agonist (PubMed:10426995, PubMed:11441098, PubMed:12874328).  Plays a complicated role in bacterial interactions with the host immune system; some effects favor the host (induces interleukin 1-beta and IL-12 p40 (IL12B), both increase the host's immune response) while others favor the bacteria (increases growth in monocyte-derived macrophages and decreases host MHC class II (MHC-II) expression and antigen processing) (PubMed:16177361).  Induces host (human and mouse) IL-12 p40 (IL12B, a pro-inflammatory cytokine) release by monocyte cell lines via TLR2 and CD14 (PubMed:10426995).  Induces host (human) monocytes to produce TNF-alpha, IL-6 and IL-12 p40; LpqH is a more potent inducer than PstS1 (PubMed:16622205).  Inhibits MHC-II expression and antigen processing in host (mouse) macrophages via TLR2 (independently of TLR4) probably via the lipid modification (PubMed:11441098).  Stimulates host (human) dendritic cell maturation to become MHC-II-positive antigen presenting cells via TLR2, which depends on lipidation; nonlipidated protein does not stimulate maturation (PubMed:11160304).  Inhibits host (human and mouse) IFN-gamma signaling in macrophages via TLR2; decreases IFN-gamma stimulated MHC-II antigen processing as well as decreasing IFN-gamma-mediated up-regulation of immunoglobulin gamma Fc receptor (FCGR1A), enabling the bacteria to evade the immune system (PubMed:12874328).  In resting human CD4+ T-cells lipidated (but probably not nonlipidated protein) is a costimulatory ligand (with anti-CD3 and anti-CD28) for T-cell proliferation and IFN-gamma and IL-2 production (PubMed:21078852).  Human CD4+ T-cells probably use TLR1/TLR2 heterodimers to respond to mycobacterial lipoproteins (PubMed:21078852).  Acting via TLR2 enhances expression of host peroxisome proliferator-activated receptor gamma (PPARG), a regulator of inflammation and immunoregulation, and increases p38 MAPK phosphorylation, IL-6 and TNF-alpha expression (PubMed:25504154).  Native or nonlipidated recombinant protein missing the first 4 residues have been shown to induce apoptosis in the human macrophage cell line THP-1 and human monocyte-derived macrophages in a TLR2, caspase-3 and caspase-8-dependent manner (PubMed:12594264).  Protein overexpressed in M. smegmatis (lipidated and probably glycosylated) induces apoptosis in human macrophages via TLR2 in a caspase-3/caspase-8-mediated manner, but also in a caspase-independent manner where mitochondrial apoptosis-inducing factor (AIFM1) translocates to the nucleus (PubMed:23316255).  Another study found mature, native (lipidated) protein did not induce apoptosis in THP-1 macrophage cell line (PubMed:12874328).  Functions as an adhesin, binds to human and mouse macrophages (PubMed:25359607).
What are the official names of this protein?
Lipoprotein LpqH, 19 kDa lipoprotein antigen, Putative transporter LpqH, p19.
What is the protein family that this protein belongs to?
Belongs to the mycobacterial 19 kDa antigen family.
What are the subcellular locations of this protein?
Cell membrane; Lipid-anchor. Secreted, cell wall. Cell surface. Secreted. Extracellular vesicle, bacterial extracellular vesicle. Host cytoplasm. Note=A soluble cell wall-associated protein (PubMed:10426995). Also found in culture filtrate in increasing quantities during growth (PubMed:1906192, PubMed:16098710). Following infection of mouse macrophage cell line J774A.1 with live (but not heat-killed) bacteria the protein is released in host cytoplasm at 1 hr but decreases dramatically by 3 hrs: release into the host requires protein lipidation and traffics from the immature phagosome through the host class I MHC antigen peptide presentation pathway (PubMed:11123323). Present in bacterial extracytoplasmic vesicles, both in mouse macrophages and in culture media (PubMed:21364279). Immunoelectron microscopy indicates this protein is close to the cell surface (PubMed:25041568).