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Cyclin-dependent kinase inhibitor 3 (CDKN3) is a member of the dual specificity protein phosphatase family. CDKN3 was identified as a cyclin-dependent kinase inhibitor, and was shown to interact with, and dephosphorylate CDK2 kinase, consequently prevent the activation of CDK2 kinase. In addition CDKN3 is important in cell cycle regulation. The CDKN3 gene was reported to be deleted, mutated, or overexpressed in several kinds of cancers.

KLRC2 has a part as a receptor for the recognition of MHC class I HLA-E molecules by NK cells and some cytotoxic T-cells. The group, designated KLRC (NKG2) are expressed mainly in natural killer (NK) cells and encodes a family of transmembrane proteins categorized by a type II membrane orientation (extracellular C terminus) and the presence of a C-type lectin domain. The KLRC (NKG2) gene family is situated inside the NK complex, a region which holds a few C-type lectin genes specially expressed on NK cells. KLRC2 alternative splice variants are known but their full-length nature is yet to be determined.

GST family of enzymescomprises a long list of cytosolic, mitochondrial, and microsomalproteinsthat are 45-55 kDa (dimer form) size and are capable of multiple reactions with a multitude of substrates, both endogenousand xenobiotic. GST catalyses the conjugation of reduced glutathione meaning the sulfhydryl group, to electrophilic centers on a wide variety of substrates. This activity is useful in the detoxification of endogenous compounds such as peroxidised lipids, as well as the metabolism of xenobiotics. GST binds toxins and function as transport protein. Glutathione S-transferase is used to create the so-called 'GST gene fusion system'. The GST is used to purify and detect proteins of interest. In a GST gene fusion system, the GST sequence is incorporated into an expression vector alongside the gene sequence encoding the protein of interest. Induction of protein expression from the vector's multiple cloning sites results in expression of a fusion protein - the protein of interest fused to the GST protein. This GST-fusion protein can then be purified from cells via its high affinity for glutathione. Fusion proteins offer an important biological assay for direct protein-to-protein interactions. The GST tag has the size of 220 amino acids, which, compared to other tags like the myc- or the FLAG-tag, is quite big. It is fused to the N-terminusof a protein. However, many commercially-available sources of GST-tagged plasmids include a thrombindomain for cleavage of the GST tag during protein purification. A GST-tag is often used to separate and purify proteins that contain the GST-fusion. GST-fusion proteins can be produced in Escherichia coli, as recombinant proteins.

Treponema pallidum is a gram-negative spirochaete bacterium and is considered to be metabolically crippled. There are at least four known subspecies: T. pallidum pallidum, T. pallidum pertenue, T. pallidum carateum and T. pallidum endemicum. The helical structure of T. pallidum pallidum allows it to move in a corkscrew motion through viscous mediums such as mucus. Treponema pallidum sub sp. pallidum has one of the smallest bacterial genomes at 1.14 million base pairs (Mb) and has limited metabolic capabilities, reflecting its adaptation through genome reduction to the rich environment of mammalian tissue.

Dihydrofolate reductase (DHFR) is an enzyme that reduces dihydrofolic acid to tetrahydrofolic acid, with NADPH as electron donor that can be converted to the kinds of tetrahydrofolate cofactors applied in 1-carbon transfer chemistry. DHFR converts dihydrofolate into tetrahydrofolate, which is a methyl group shuttle required for the de novo synthesis of purines, thymidylic acid, and specific amino acids. Even though the functional DHFR gene is mapped to chromosome 5, numerous intronless processed pseudogenes or dihydrofolate reductase-like genes are identified on separate chromosomes.
DHFR deficiency is associated with megaloblastic anemia.DHFR knockdown plays a role in the anticancer activity of 2-hydroxyoleic acid.
DHFR gene insertion/deletion polymorphism is linked to variation in serum and red blood cell folate concentrations in women.

HIV-1 and HIV-2 appear to package their RNA differently. HIV-1 binds to any appropriate RNA whereas HIV-2 preferentially binds to mRNA which creates the Gag protein itself. This means that HIV-1 is better able to mutate. HIV-2 is transmitted in the same ways as HIV-1: Through exposure to bodily fluids such as blood, semen, tears and vaginal fluids. Immunodeficiency develops more slowly with HIV-2.
HIV-2 is less infectious in the early stages of the virus than with HIV-1.
The infectiousness of HIV-2 increases as the virus progresses.
Major differences include reduced pathogenicity of HIV-2 relative to HIV-1, enhanced immune control of HIV-2 infection and often some degree of CD4-independence. Despite considerable sequence and phenotypic differences between HIV-1 and 2 envelopes, structurally they are quite similar. Both membrane-anchored proteins eventually form the 6-helix bundles from the N-terminal and C-terminal regions of the ectodomain, which is common to many viral and cellular fusion proteins and which seems to drive fusion.
HIV-1 gp41 helical regions can form more stable 6-helix bundles than HIV-2 gp41 helical regions however HIV-2 fusion occurs at a lower threshold temperature (25°C), does not require Ca2+ in the medium, is insensitive to treatment of target cells with cytochalasin B, and is not affected by target membrane glycosphingolipid composition.

Pancreatitis-associated protein (PAP) is a secretory protein not normally expressed in healthy pancreas but highly induced during acute pancreatitis. While PAP has been shown to be anti-bacterial and antiapoptotic in vitro, its definitive biological function in vivo is not clear. Using antisepse oligonucleotides, inhibition of PAP expression significantly worsened pancreatitis in a rat model. During pancreatitis, PAP released by the pancreas could mediate lung inflammation through induction of hepatic TNF- alpha expression and subsequent increase in circulating TNF-alpha.
PAP is activated in primary liver cancers. In normal liver, the protein is undetectable in normal mature hepatocytes and found only in some ductular cells, representing potential hepatic progenitor cells. PAP can be considered hepatic cytokine that combines mitogenic and anti-apoptotic functions regarding hepatocytes, and consequently acts as a growth factor in vivo to enhance liver regeneration. In pancreatic cancor, PAP was overexpressed in 79% (30 of 38) of pancreatic ductal adenocarcinoma, 19% (7 of 36) of chronic pancreatitis, and 29% (2 of 7) of mucinous cystadenoma. PAP was found in malignant ductular structures in pancreatic carcinomas as well as in benign proliferating ductules and acinar cells in chronic pancreatitis. Elevation of PAP in patients with pancreatic cancer is not merely explainable by concomitant pancreatitis, but seems to be due to increased PAP production by the cancer cells and is also correlated to tumour load as expressed by the UICC stages.
Epithelial expression of PAP was induced under intestinal mucosal inflammation initiated by exposure to commensal bacteria or DSS as well as inflamed IBD colon. Increased serum level of PAP diagnosed ileal location in active Crohn disease with a sensitivity of 60%, a specificity of 94%, a positive predictive value of 84% and a negative predictive value of 81%. Elevated serum PAP (> 50 ng/mL) is significantly associated with disease activity and ileal location of Crohn disease.

The human cytomegalovirus UL99-encoded pp28 is a myristylated phosphoprotein that is a constituent of the virion. The pp28 protein is positioned within the tegument of the virus particle, a protein structure that resides between the capsid and envelope. In the infected cell, pp28 is found in a cytoplasmic compartment derived from the Golgi apparatus, where the virus buds into vesicles to acquire its final membrane.

DACT3 which belongs to the DACT (Dpr/Frodo) gene family plays an imperative role in a negative regulator of Wnt/-catenin signaling. Unlike other Wnt signaling inhibitors that are silenced by DNA methylation, DACT3 repression is linked to bivalent histone modifications.

HCV is a small 50nm, enveloped, single-stranded, positive sense RNAvirus in the family Flaviviridae. HCV has a high rate of replication with approximately one trillion particles produced each day in an infected individual. Due to lack of proofreading by the HCV RNA polymerase, the HCV has an exceptionally high mutation rate, a factor that may help it elude the host's immune response. Hepatitis C virus is classified into six genotypes(1-6) with several subtypes within each genotype. The preponderance and distribution of HCV genotypes varies globally. Genotype is clinically important in determining potential response to interferon-based therapy and the required duration of such therapy. Genotypes 1 and 4 are less responsive to interferon-based treatment than are the other genotypes (2, 3, 5 and 6).

Trichomonas vaginalis, an anaerobic, flagellated protozoan parasite, is most dominant protozoan causing sexual transmitted disease. T. vaginalis induced vaginal tract infection occurs as multiple steps involving interactions between host macromolecules and protozoan virulent factor. Adhension protein P65 of T. vaginalis has a vital part in assisting the penetration into vaginal tract surface.

SHMT1 is a member of the SHMT family. SHMT1 is the cellular form of serine hydroxymethyltransferase, a pyridoxal phosphate-containing enzyme which catalyzes the reversible conversion of serine and tetrahydrofolate to glycine and 5 10-methylene tetrahydrofolate. In addition, SHMT1 specifically provides one-carbon units for thymidylate biosynthesis, reduces methylenetetrahydrofolate pools for S-adenosylmethionine (SAM) synthesis by synthesizing serine, sequesters 5-methyltetrahydrofolate and inhibits SAM synthesis.

MYC Induced Nuclear Antigen, also known as MINA is an oxygenase which can function both as a histone lysine demethylase and a ribosomal histidine hydroxylase. MINA is involved in the demethylation of trimethylated Lys-9 on histone H3 (H3K9me3), leading to an increase in ribosomal RNA expression. MINA also catalyzes the hydroxylation of 60S ribosomal protein L27a on His-39. In addition, MINA plays a significant role in cell growth and survival. MINA is implicated in ribosome biogenesis, probably in the duration of the assembly process of pre-ribosomal particles.

BCL2-associated athanogene 2 (BAG2) belongs to the Bag family of proteins. BAG2 is a chief component of the HSC 70/CHIP chaperone-dependent ubiquitin ligase complex and acts to upset CHIP-mediated ubiquitylation. BAG proteins compete with Hip for attaching to the Hsc70/Hsp70 ATPase domain and promote substrate discharge. All the BAG proteins have a roughly 45 amino acid BAG domain by the C-terminus but vary clearly in their N-terminal regions. The BAG domains of BAG1, BAG2, and BAG3 act together expressly with the Hsc70 ATPase domain in vitro and in mammalian cells. All three proteins attach with high affinity to the ATPase domain of Hsc70 and obstruct its chaperone activity in a Hip-repressible manner.

Melanoma Antigen Family A 8, also known as MAGEA8 belongs to the MAGE gene family, which includes twelve known genes, of which six are expressed in tumors. Furthermore, the MAGE genes were at first isolated from different kinds of tumors, and according to their virtually exclusive tumor-specific expression in adult tissues, they have been used as targets for cancer immunotherapy.

NCS1 is part of the neuronal calcium sensor gene family, which encode calcium-binding proteins expressed primarily in neurons. NCS1 regulates G protein-coupled receptor phosphorylation in a calcium-dependent manner and can substitute for calmodulin. NCS1 is related with secretory granules and modulates synaptic transmission and synaptic plasticity. NCS1 regulates GRK1 and substitutes for calmodulin. NCS1 stimulates PI4KB kinase activity and participates in long-term synaptic plasticity through its interaction with PICK1. NCS1 takes part in neuron differentiation through inhibition of the activity of N-type voltage-gated calcium channel.

CBR1 is a NADPH-dependent, monomeric, and cytosolic enzyme which is related to a family of short-chain dehydrogenases/reductases. CBR1 protein (277 a.a.) is broadly spread in human tissues such as liver, epidermis, stomach, small intestine, kidney, neuronal cells, and smooth muscle fiber. CBR1 metabolizes numerous toxic environmental quinones and pharmacological relevant substrates such as the anticancer drug, doxorubicin. The best substrates of CBR1 are quinones, including ubiquinone-1 and tocophrolquinone (vitamin E).

Cofilin is a family of actin-binding proteins which disassembles actin filaments. It is a widely distributed intracellular actin-modulating protein that binds and depolymerizes filamentous F-actin and inhibits the polymerization of monomeric G-actin in a pH-dependent manner. It is involved in the translocation of actin-cofilin complex from cytoplasm to nucleus.

Peptidylprolyl Isomerase C (PPIC) belongs to the peptidyl-prolyl cis-trans isomerase (PPIase) family. PPIases catalyze the cis-trans isomerization of proline imidic peptide bonds in oligopeptides and hasten the folding of proteins. Like other PPIases, PPIC binds immunosuppressant cyclosporin A.

Calpain, Small Subunit 1 (CAPNS1) belongs to the calpain small subunit family. Calpains are a ubiquitous, well-conserved family of calcium-dependent, cysteine proteases, widely distributed in mammalian cells. Calpain families are implicated in neurodegenerative processes, considering that their activation can be triggered by calcium influx and oxidative stress. Calpains function as heterodimers, comprising a specific large catalytic subunit (calpain 1 subunit in Calpain I, and calpain 2 subunit in Calpain II), and a common small regulatory subunit encoded by the CAPNS1 gene. The CAPNS1 protein is vital for the stability and function of both calpain heterodimers, whose proteolytic activities influence numerous cellular functions including apoptosis, proliferation, migration, adhesion, and autophagy.

SULT2A1 is a member fo the sulfotransferase family. SULT2A1 is primarily expressed in liver and adrenal tissues, and to a lesser extent in kidney. SULT2A1 catalyzes the 3'-phosphoadenosine 5'-phosphosulfate-dependent sulfation of an extensive selection of steroids in human liver and adrenal tissues, and in addition is responsible for a larg number of the sulfation of bile acids in human liver.

ARG2 participates in the regulation of extra-urea cycle arginine metabolism and also in down-regulation of nitric oxide synthesis. Extrahepatic arginase functions to regulate L-arginine bioavailability to NO synthase. Since NO synthase is found in the penile corpus cavernosum smooth muscle, the clitoral corpus cavernosum and the vagina, ARG2 takes part in both male and female sexual arousal and therefore a potential target for the treatment of male and female sexual arousal disorders.

SARS Coronavirus is an enveloped virus containing three outer structural proteins, namely the membrane (M), envelope (E), and spike (S) proteins. Spike (S)-glycoprotein of the virus interacts with a cellular receptor and mediates membrane fusion to allow viral entry into susceptible target cells. Accordingly, S-protein plays an important role in virus infection cycle and is the primary target of neutralizing antibodies.It has recently been shown that SARS is caused by a human coronavirus. Human coronaviruses are the major cause of upper respiratory tract illness in humans, such as the common cold. Coronaviruses are positive-stranded RNA viruses, featuring the largest viral RNA genomes known to date (27-31 kb). The first step in coronavirus infection is binding of the viral spike protein, a 139-kDa protein, to certain receptors on host cells. The spike protein is the main surface antigen of the coronavirus. The most prominent protein in the culture supernatants infected with SARS virus is a 46 kDa nucleocapsid protein. This suggests that the nucleocapsid protein is a major immunogen that may be useful for early diagnostics.