U6 snRNA-Associated Sm-Like Protein LSm1 (LSM1) belongs to the snRNP Sm proteins family. The Sm-like proteins are thought to form a stable heteromer present in tri-snRNP particles, which plays an important role in pre-mRNA splicing. LSM1 binds specifically to the 3-terminal U-tract of U6snRNA. LSM1 can interact with SLBP when histone mRNA is being rapidly degraded during the S phase. In addition, LSM1 is associated with cellular transformation and the progression of several malignancies including mesothelioma, lung cancer and breast cancer.
U6 snRNA-associated Sm-like protein LSm4 (LSM4) is a member of the snRNP Sm proteins family. Sm-like proteins contain the Sm sequence motif and are thought to form a stable heteromer present in tri-snRNP particles, which are important for pre-mRNA splicing. LSM4 forms a heteromer with a donut shape. The complexes are involved in various steps of RNA metabolism. LSM4 binds specifically to the 3-terminal U-tract of U6 snRNA. LSM4 contributes RNA protein interactions and structural changes which are essential during ribosomal subunit assembly.
LTA4H, which is short for Leukotriene A-4 hydrolase, is a 611 aa. protein. It belongs to the peptidase M1 family, and exists in cytoplasm. This protein has at least 4 isforms produced by alternative splicing, and two of them are expressed in monocytes, lymphocytes, neutrophils, reticulocytes, platelets and fibroblasts. LTA4H involves in lipid metabolism and leukotriene B4 biosynthesis. It is a epoxide hydrolase that catalyzes the final step in the biosynthesis of the proinflammatory mediator leukotriene B4. It also has aminopeptidase activity
Leukotriene A-4 hydrolase, also known as LTA-4 hydrolase, Leukotriene A (4) hydrolase, LTA4H and LTA4, is cytoplasm protein which belongs to thepeptidase M1 family. LTA4H hydrolyzes an epoxide moiety of leukotriene A4 (LTA-4) to form leukotriene B4 (LTB-4). This enzyme also has some peptidase activity. The leukotrienes (LTs) are a class of structurally related lipid mediators involved in the development and maintenance of inflammatory and allergic reactions. In the biosynthesis of LTs, arachidonic acid was converted into the unstable intermediate epoxide LTA4, which may in turn be conjugated with glutathione to form the spasmogenic LTC4, or hydrolyzed into the proinflammatory lipid mediator LTB4 in a reaction catalyzed by Leukotriene A4 hydrolase (LTA4H). LTB4 is a classical chemoattractant of human neutrophils and triggers adherence and aggregation of leukocytes to vascular endothelium, and also modulates immune responses. As a bifunctional zinc metalloenzyme, LTA4H also exhibits an anion-dependant arginyl aminopeptidase activity of high efficiency and specificity in addition to its epoxide hydrolase activity. LTA4H is regarded as a therapeutic target for inflammation.
Tumor necrosis factor receptor superfamily member 3; also known as Lymphotoxin-beta receptor;Tumor necrosis factor C receptor;Tumor necrosis factor receptor 2-related protein;Tumor necrosis factor receptor type III;LTBR;TNFCR; TNFR3 and TNFRSF3; is a member of the tumor necrosis factor (TNF) family of receptors. LTBR is a single-pass type I membrane protein and contains four TNFR-Cys repeats. It is expressed on the surface of most cell types; but not on T and B lymphocytes. LTBR and its ligand play a role in the development and organization of lymphoid tissue and transformed cells. Activation of LTBR can trigger apoptosis. In addition; LTBR can lead to the release of the cytokine interleukin 8.
Leukotriene C4 synthase, also known as LTC4 synthase, Leukotriene-C(4) synthase, and LTC4S, is a multi-pass membrane protein which belongs to theMAPEG family. LTC4S is detected in lung, platelets and the myelogenous leukemia cell line KG-1 (at protein level). LTC4S activity is present in eosinophils, basophils, mast cells, certain phagocytic mononuclear cells, endothelial cells, vascular smooth muscle cells and platelets. LTC4S is essential for the production of cysteinyl leukotrienes (Cys-LT), critical mediators in asthma. Mutagenic analysis of the conjugation function of human LTC4S has identified R51 and Y93 as critical for acid and base catalysis of LTA4 and reduced glutathione, respectively. A comparison across species for proteins that possess LTC4S activity reveals conservation of both of these residues, whereas R51 is absent in the FLAP molecules. Thus, within the glutathione S-transferase superfamily of genes, alignment of specific residues allows the separation of LTC4S family members from their most structurally similar counterparts, the FLAP molecules. Defects in LTC4S are the cause of leukotriene C4 synthase deficiency (LTC4 synthase deficiency). LTC4 synthase deficiency is a fatal neurometabolic developmental disorder. It is associated with muscular hypotonia, psychomotor retardation, failure to thrive, and microcephaly.
Lactotransferrin is a member of the transferrin family that transfer iron to the cells and control the level of free iron in the blood and external secretions. Lactotransferrin is a secreted protein and contains two transferrin-like domains. Lactotransferrin can be cleaved into the following four chains: Kaliocin-1, Lactoferroxin-A, Lactoferroxin-B, and Lactoferroxin-C. Lactoferroxin A, Lactoferroxin B, and Lactoferroxin C have opioid antagonist activity. Lactoferroxin A shows preference for mu-receptors, while Lactoferroxin B and Lactoferroxin C have somewhat higher degrees of preference for kappa-receptors than for mu-receptors. LTF has antimicrobial activity (bacteriocide, fungicide) and is part of the innate defense, mainly at mucoses.
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