241 human active and 13 inactive phosphatases in total;
194 phosphatases have substrate data;
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336 protein substrates;
83 non-protein substrates;
1215 dephosphorylation interactions;
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299 KEGG pathways;
876 Reactome pathways;
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last scientific update: 11 Mar, 2019
Endoplasmic reticulum membrane Endoplasmic reticulum MelanosomeNote=Identified by mass spectrometry in melanosome fractions fromstage I to stage IV (PubMed:12643545, PubMed:17081065) Thepalmitoylated form preferentially localizes to the perinuclearrough ER (PubMed:22314232)
Function (UniProt annotation)
Calcium-binding protein that interacts with newlysynthesized glycoproteins in the endoplasmic reticulum It may actin assisting protein assembly and/or in the retention within theER of unassembled protein subunits It seems to play a major rolein the quality control apparatus of the ER by the retention ofincorrectly folded proteins Associated with partial T-cellantigen receptor complexes that escape the ER of immaturethymocytes, it may function as a signaling complex regulatingthymocyte maturation Additionally it may play a role in receptor-mediated endocytosis at the synapse
The endoplasmic reticulum (ER) is a subcellular organelle where proteins are folded with the help of lumenal chaperones. Newly synthesized peptides enter the ER via the sec61 pore and are glycosylated. Correctly folded proteins are packaged into transport vesicles that shuttle them to the Golgi complex. Misfolded proteins are retained within the ER lumen in complex with molecular chaperones. Proteins that are terminally misfolded bind to BiP and are directed toward degradation through the proteasome in a process called ER-associated degradation (ERAD). Accumulation of misfolded proteins in the ER causes ER stress and activates a signaling pathway called the unfolded protein response (UPR). In certain severe situations, however, the protective mechanisms activated by the UPR are not sufficient to restore normal ER function and cells die by apoptosis.
Phagocytosis is the process of taking in relatively large particles by a cell, and is a central mechanism in the tissue remodeling, inflammation, and defense against infectious agents. A phagosome is formed when the specific receptors on the phagocyte surface recognize ligands on the particle surface. After formation, nascent phagosomes progressively acquire digestive characteristics. This maturation of phagosomes involves regulated interaction with the other membrane organelles, including recycling endosomes, late endosomes and lysosomes. The fusion of phagosomes and lysosomes releases toxic products that kill most bacteria and degrade them into fragments. However, some bacteria have strategies to escape the bactericidal mechanisms associated with phagocytosis and survive within host phagocytes.
Thyroid hormones triiodothyronine (T3) and thyroxine (T4) are essential for normal development, growth and metabolic homeostasis in all vertebrates, and synthesized in the thyroid gland. The functional unit of the thyroid gland is the follicle, delimited by a monolayer of thyrocytes. Polarized thyrocytes surround the follicular lumen; with their basal and apical surfaces facing the bloodstream and the lumen, respectively. To synthesize thyroid hormones, thyrocytes take up iodide at their basal side and concentrate it into the lumen. They also secrete in this lumen the specialized protein thyroglobulin (TG) which serves as a store for the hormones. In the follicular lumen oxidation of iodine, iodination of tyrosines (MIT, 3-monoiodotyrosine; DIT, 3,5-diiodotyrosine) and coupling of iodotyrosines takes place on tyrosine residues in TG, resulting in T3 and T4 synthesis. Iodinated TG is resorbed through the apical membrane and degraded to form T3/T4 in lysosomes; the T3/T4 is then secreted through the basal membrane.
Human T-cell leukemia virus type 1 (HTLV-1) is a pathogenic retrovirus that is associated with adult T-cell leukemia/lymphoma (ATL). It is also strongly implicated in non-neoplastic chronic inflammatory diseases such as HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Expression of Tax, a viral regulatory protein is critical to the pathogenesis. Tax is a transcriptional co-factor that interfere several signaling pathways related to anti-apoptosis or cell proliferation. The modulation of the signaling by Tax involve its binding to transcription factors like CREB/ATF, NF-kappa B, SRF, and NFAT.
Following synthesis on membrane-bound ribosomes, the three viral integral membrane proteins, HA (hemagglutinin), NA (neuraminidase) and M2 (ion channel) enter the host endoplasmic reticulum (ER) where all three are folded and HA and NA are glycosylated. Subsequently HA is assembled into a trimer. HA, NA and M2 are transported to the Golgi apparatus where cysteine residues on HA and M2 are palmitoylated. Furin cleaves HA into HA1 and HA2 subunits and all three proteins are directed to the virus assembly site on the apical plasma membrane via apical sorting signals. The signals for HA and NA reside on the transmembrane domains (TMD) while the sorting signal for M2 is not yet characterized. The TMDs of HA and NA also contain the signals for lipid raft association. Lipid rafts are non-ionic detergent-resistant lipid microdomains within the plasma membrane that are rich in sphingolipids and cholesterol. Examination of purified virus particles indicates that influenza virus buds preferentially from these microdomains
Antigen presenting cells (APCs) such as B cells, dendritic cells (DCs) and monocytes/macrophages express major histocompatibility complex class II molecules (MHC II) at their surface and present exogenous antigenic peptides to CD4+ T helper cells. CD4+ T cells play a central role in immune protection. On their activation they stimulate differentiation of B cells into antibody-producing B-cell blasts and initiate adaptive immune responses. MHC class II molecules are transmembrane glycoprotein heterodimers of alpha and beta subunits. Newly synthesized MHC II molecules present in the endoplasmic reticulum bind to a chaperone protein called invariant (Ii) chain. The binding of Ii prevents the premature binding of self antigens to the nascent MHC molecules in the ER and also guides MHC molecules to endocytic compartments. In the acidic endosomal environment, Ii is degraded in a stepwise manner, ultimately to free the class II peptide-binding groove for loading of antigenic peptides. Exogenous antigens are internalized by the APC by receptor mediated endocytosis, phagocytosis or pinocytosis into endocytic compartments of MHC class II positive cells, where engulfed antigens are degraded in a low pH environment by multiple acidic proteases, generating MHC class II epitopes. Antigenic peptides are then loaded into the class II ligand-binding groove. The resulting class II peptide complexes then move to the cell surface, where they are scanned by CD4+ T cells for specific recognition (Berger & Roche 2009, Zhou & Blum 2004, Watts 2004, Landsverk et al. 2009)
Interleukin 35 (IL35) is an IL12 family cytokine produced by regulatory but not effector T-cells. It is a dimeric protein composed of IL-12RB2 and IL27RA chains. IL35 suppresses inflammatory responses of immune cells
The unfolded protein is recognized by a chaperon protein (calnexin or calreticulin) and the folding process starts. The binding of these protein requires a mono-glucosylated glycan (Caramelo JJ and Parodi AJ, 2008), but in certain cases can occur even in the absence of glycosylation (Ireland BS et al, 2008)
Interleukin-27 (IL27) is a heterodimeric cytokine that contains Epstein-Barr virus–induced gene 3 (EBI3) and IL27p28 (IL27). It signals through a receptor composed of Interleukin-6 receptor subunit beta (IL6ST, gp130), which is utilized by many cytokines, and Interleukin-27 receptor subunit alpha (IL27RA, WSX-1, TCCR) (Yoshida & Hunter 2015)
Unlike other glycoproteins, correct folding of MHC class I molecules is not sufficient to trigger their exit from the ER, they exit only after peptide loading. Described here is the process of antigen presentation which consists of the folding, assembly, and peptide loading of MHC class I molecules. The newly synthesized MHC class I Heavy Chain (HC) is initially folded with the help of several chaperones (calnexin, BiP, ERp57) and then binds with Beta-2-microglobulin (B2M). This MHC:B2M heterodimer enters the peptide loading complex (PLC), a multiprotein complex that includes calreticulin, endoplasmic reticulum resident protein 57 (ERp57), transporter associated with antigen processing (TAP) and tapasin. Peptides generated from Ub-proteolysis are transported into the ER through TAP. These peptides are further trimmed by ER-associated aminopeptidase (ERAP) and loaded on to MHC class I molecules. Stable MHC class I trimers with high-affinity peptide are transported from the ER to the cell surface by the Golgi apparatus
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