paf

Platelet-Activating Factor Acetylhydrolase IB Subunit β (PAFAHB) is a cytoplasmic hydrolase. PAFAHB is a member of the GDSL lipolytic enzyme family. It also belongs to Platelet-activating factor acetylhydrolase IB beta gamma subunits subfamily. Cytosolic PAF-AH IB is formed of three subunits of 45 kDa (alpha), 30 kDa (beta) and 29 kDa (gamma), PAFAHB is a catalytic subunit. PAFAHB inactivates PAF by removing the acetyl group at the sn-2 position.

Platelet-Activating Factor Acetylhydrolase (PAFAH) is a secreted enzyme which belongs to the AB hydrolase superfamily and Lipase family and catalyzes the degradation of platelet-activating factor to biologically inactive products. PAFAH is produced by inflammatory cells and hydrolyzes oxidised phospholipids in LDL. PAFAH has been implicated in the development of atherosclerosis and has also been identified as a marker for cardiac disease. PAFAH might have a major physiologic effect in the presence of inflammatory bodily responses. PAFAH alters the action of PAF by hydrolyzing the sn-2 ester bond to yield the biologically inactive lyso-PAF. PAFAH has specificity for substrates with a short residue at the sn-2 position.

KIAA11, also known as p15(PAF), is a proliferating cell nuclear antigen-associated factor that interacts with proliferating cell nuclear antigen(PCNA). It was initially isolated in a yeast two-hybrid screen for PCNA binding partners and was shown to bind PCNA competitively with the cell cycle regulator p21(WAF). KIAA11 is localized primarily in the nucleus. It shares the conserved PCNA binding motif with several other PCNA binding proteins including CDK inhibitor p21. KIAA11 is involved in cell proliferation and plays a role in early tumor recurrence (ETR), and prognosis of hepatocellular carcinoma (HCC). KIAA11 is expressed predominantly in the liver, pancreas, and placenta. It cannot be detected in the heart or brain. It is highly expressed in some tumors, especially esophageal tumors, in anaplastic thyroid carcinomas, and non-small-cell lung cancer lines. Overexpression of KIAA11 predicts high stage, early tumor recurrence, and poor prognosis of hepatocellular carcinoma. It also may be involved in the protection of cells from UV-induced cell death.

Lecithin:cholesterol acyltransferase (LCAT) is the only enzyme capable of esterifying cholesterol in plasma, thus determining the maturation of high-density lipoproteins. Because it maintains an unesterified cholesterol gradient between peripheral cells and extracellular acceptors, for a long time, LCAT has been considered as a key enzyme in reverse cholesterol transport.

IL-5 is expressed in eosinophils, NK cells, TC2 CD8+ T cells, mast cells, CD45+ CD4+ T cells, gamma delta T cells and IL-1 beta activated endothelial cells. IL-5 acts as a growth and differentiation factor for both B cells and eosinophils. Relative to B cells, IL-5 appears to induce the differentiation of activated conventional B-2 cells into Ig-secreting cells. In addition, it induces the growth of B-1 progenitors as well as IgM production by B-1 cells.IL-5 appears to perform a number of functions on eosinophils. These include the down modulation of Mac-1,the upregulation of receptors for IgA and IgG,the stimulation of lipid mediator (leukotriene C4 and PAF) secretion and the induction of granule release.IL-5 also promotes the growth and differentiation of eosinophils.

Secretory calcium-dependent phospholipase A2 that primarily targets extracellular phospholipids. Hydrolyzes the ester bond of the fatty acyl group attached at sn-2 position of phospholipids with preference for phosphatidylcholines and phosphatidylglycerols over phosphatidylethanolamines. Preferentially releases sn-2 omega-6 and omega-3 polyunsaturated fatty acyl (PUFA) chains over saturated fatty acyls. Contributes to phospholipid remodeling of very low-density lipoprotein (VLDL), low-density lipoprotein (LDL) and high-density lipoprotein (HDL) particles. Hydrolyzes LDL phospholipids releasing unsaturated fatty acids that regulate macrophage differentiation toward foam cells. Efficiently hydrolyzes and inactivates PAF, a potent lipid mediator present in oxidized LDL. May act in an autocrine and paracrine manner. Secreted by lung epithelium, targets membrane phospholipids of infiltrating eosinophils, releasing arachidonate and boosting eicosanoid and cysteinyl leukotriene synthesis involved in airway inflammatory response. Secreted by gut epithelium, hydrolyzes dietary and biliary phosphatidylcholines in the gastrointestinal lumen, thereby regulating adipogenesis and body weight. Plays a stem cell regulator role in colon epithelium. Within intracellular compartment, mediates Paneth-like cell differentiation and its stem cell supporting functions by inhibiting Wnt signaling pathway in intestinal stem cell (ISC). Secreted in the intestinal lumen upon inflammation, acts in an autocrine way and promotes prostaglandin E2 synthesis that stimulates the Wnt signaling pathway in ISCs and tissue regeneration. May participate in hair follicle morphogenesis by regulating phosphatidylethanolamines metabolism at the outermost epithelial layer and facilitating melanin synthesis. By generating lysophosphatidylcholines (LPCs) at sperm acrosome controls sperm cell capacitation, acrosome reaction and overall fertility. May promote neurite outgrowth in neuron fibers involved in nociception. Contributes to lipid remodeling of cellular membranes and generation of lipid mediators involved in pathogen clearance. Cleaves sn-2 fatty acyl chains of phosphatidylglycerols and phosphatidylethanolamines, which are major components of membrane phospholipids in bacteria. Displays bactericidal activity against Gram-positive bacteria by directly hydrolyzing phospholipids of the bacterial membrane. In pulmonary epithelium, may contribute to host defense response against adenoviral infection. Prevents adenovirus entry into host cells by hydrolyzing host cell plasma membrane, releasing C16:0 LPCs that inhibit virus-mediated membrane fusion and viral infection. Likely prevents adenoviral entry into the endosomes of host cells. May play a role in maturation and activation of innate immune cells including macrophages, group 2 innate lymphoid cells and mast cells.