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Cytokeratin 5 (KRT5) belongs to the keratin gene family. The type II cytokeratins are comprised of basic or neutral proteins which are arranged in pairs of heterotypic keratin chains coexpressed throughout differentiation of simple and stratified epithelial tissues. The type II cytokeratins are clustered in a region of chromosome 12q12-q13. The KRT5 type II cytokeratin is specifically expressed in the basal layer of the epidermis with family member KRT14. Mutations in these genes are linked with a complex of diseases termed epidermolysis bullosa simplex.

The 14-3-3 family of proteins plays a key regulatory role in signal transduction, checkpoint control, apoptotic and nutrient-sensing pathways. 14-3-3 proteins are highly conserved and ubiquitously expressed. There are at least seven isoforms, β, γ, ε, σ, ζ, τ and η that have been identified in mammals. The 14-3-3 epsilon, a subtype of the 14-3-3 family of proteins, was thought to be brain and neuron-specific. It has been shown to interact with CDC25 phosphatases, RAF1 and IRS1 proteins, suggesting its role in diverse biochemical activities related to signal transduction, such as cell division and regulation of insulin sensitivity. It has also been implicated in the pathogenesis of small cell lung cancer.

Cathepsin D is synthesized as a 54kDa precursor, which is proteolytically processed to an intermediate 48kDa single chain, which matures into more stable 34kDa and 14kDa two chain form. It is an estrogen-regulated lysosomal protease that has been suggested to facilitate cancer cell migration and invasion by digesting the basement membrane, extracellular matrix, and xonnective tissue. Because of its mitogenic and proteolytic activities, it has been implicated as a prognostic marker in many tumor types. Cathepsin D is expressed in epithelial cells as well as in macrophages.

A fusion tag called FLAG consists of eight amino acids (AspTyrLysAspAspAspAspLys) including an enterokinase-cleavage site. FLAG is specifically designed for immunoaffinity chromatography. It allows elution under non-denaturing conditions. Several antibodies against this peptide have been developed. One antibody. denoted as M1. binds the peptide in the presence of bivalent metal cations. preferably Ca(+). Elution is effected by chelating agents. Another strategy is competitive elution with excess of free Flag Peptide.
The FLAG peptide purifies and detects recombinant fusion proteins. FLAG peptide is useful in Western blotting, immunocytochemistry, immunoprecipitation, flow cytometry, protein purification, and in the study of protein-protein interactions, cell ultrastructure, and protein localization. Flag peptide is a hydrophilic tag which significantly improves the detection and purification of recombinant fusion proteins.

CD31 is a glycoprotein expressed on endothelial cells, platelets, macrophages and Kupffer cells, granulocytes, T / NK cells, lymphocytes, megakaryocytes, fibroblasts, osteoclasts, neutrophils. In humans, the gene encoding CD31 is found on chromosome 17.
CD31 is a cluster of differentiation molecule. It is also called PECAM-1 for platelet endothelial cell adhesion molecule. It plays a key role in removing aged neutrophils from the body. Both the neutrophil and the macrophage express CD31 on their membranes, and during the testing process, these CD31 molecules bind the two cells together. If the neutrophil is healthy, it will send a signal to the macrophage, and the CD31 molecules will detach.
CD31 is also expressed in certain tumors, including epithelioid hemangioendothelioma, epithelioid sarcoma-like hemangioendothelioma, other vascular tumors, histiocytic malignancies, and plasmacytomas. It is rarely found in some sarcomas and carcinomas.

CD4 is a cell-surface glycoprotein found on the mature helper T cells and immature thymocytes, as well as on monocytes and macrophages. (Some cytotoxic T cells have CD4 protein as well.) Normally, about 65% of T cells in the blood are CD4+ (have CD4 protein protruding from their membrane). A mature T cell with either have CD4 or CD8, but not both. During one stage of development T cells develop CD4 and CD8 receptors, but they eventually are differentiated in the thymus and become more specialized.

CD8 is a cell surface glycoprotein found on most cytotoxic T lymphocytes that mediates efficient cell-cell interactions within the immune system. CD8 acts as a co-receptor, and the T-cell receptor on the T lymphocyte recognize antigen displayed by an antigen presenting cell (APC) in the context of class I MHC molecules. The functional CD8 is either a homodimer composed of two alpha chains, or a heterodimer composed of one alpha and one beta chain. Both alpha and beta chains share significant homology to immunoglobulin variable light chains.
CD8 identifies cytotoxic/suppressor t-cells that interact with MHC class I bearing targets. CD8 is thought to play a role in the process of t-cell mediated killing. CD8 alpha chains binds to class-I MHC molecules alpha-3 domains.

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).

Pollen allergen Car b 1 isoform (Car b 1.0109) causes an allergic reaction in humans.

The recombinant Protein A/G/L is a genetically engineered protein which combines the IgG binding profiles of all Protein A, Protein G and Protein L. Protein A/G/L is a gene fusion product. Recombinant fusion protein A/G/L is comprised of 5 Ig-binding regions of protein L (B1-B2-B3-B4-B5), 5 IgG binding domains from Protein A (E-D-A-B-C) and 2 Ig-binding region of protein G (C1-C3). The recombinant Protein A/G/L is ideal for purification of monoclonal or polyclonal IgG antibodies. Protein A/G/L binds to IgG from humans, mice, rats, cows, goats, sheep, rabbits, guinea pigs, pigs, dogs and cats.

Forty-two antigenic domains were identified across the hepatitis A virus (HAV) polyprotein by using a set of 237 overlapping 20-mer synthetic peptides spanning the entire HAV polyprotein. Nineteen antigenic domains were found within the structural proteins, and 22 were found within the nonstructural proteins, with 1 domain spanning the junction of VP1 and P2A proteins. Five of these domains were considered immunodominant, as judged by both the breadth and the strength of their immunoreactivity. One domain is located within the VP2 protein at position 57-90 aa. A second domain, located at position 767-842 aa, contains the C-terminal part of the VP1 protein and the entire P2A protein. A third domain, located at position 1403-1456 aa, comprises the C-terminal part of the P2C protein and the N-terminal half of the P3A protein. The fourth domain, located at position 1500-1519 aa, includes almost the entire P3B, and the last domain, located at position 1719-1764 aa, contains the C-terminal region of the P3C protein and the N-terminal region of the P3D protein. Four of the five most immunoreactive domains are derived from small HAV proteins and/or encompass protein cleavage sites separating different HAV proteins.

Human immunodeficiency virus (HIV) is a retrovirus that can lead to a condition in which the immune system begins to fail, leading to opportunistic infections. HIV primarily infects vital cells in the human immune system such as helper T cells (specifically CD4+ T cells), macrophages and dendritic cells. HIV infection leads to low levels of CD4+ T cells through three main mechanisms: firstly, direct viral killing of infected cells; secondly, increased rates of apoptosis in infected cells; and thirdly, killing of infected CD4+ T cells by CD8 cytotoxic lymphocytes that recognize infected cells. When CD4+ T cell numbers decline below a critical level, cell-mediated immunity is lost, and the body becomes progressively more susceptible to opportunistic infections. HIV was classified as a member of the genus Lentivirus, part of the family of Retroviridae. Lentiviruses have many common morphologies and biological properties. Many species are infected by lentiviruses, which are characteristically responsible for long-duration illnesses with a long incubation period. Lentiviruses are transmitted as single-stranded, positive-sense, enveloped RNA viruses. Upon entry of the target cell, the viral RNA genome is converted to double-stranded DNA by a virally encoded reverse transcriptase that is present in the virus particle. This viral DNA is then integrated into the cellular DNA by a virally encoded integrase so that the genome can be transcribed. Once the virus has infected the cell, two pathways are possible: either the virus becomes latent and the infected cell continues to function, or the virus becomes active and replicates, and a large number of virus particles are liberated that can then infect other cells.

IFIH1 is a DEAD box protein which is upregulated in response to treatment with beta-interferon and a protein kinase C-activating compound, mezerein. Irreversible reprogramming of melanomas can be attained by therapy with both these agents; treatment with either agent alone only achieves reversible differentiation. DEAD box proteins are implicated in several cellular processes involving alteration of RNA secondary structure such as translation initiation, nuclear and mitochondrial splicing, and ribosome and spliceosome assembly.

Babesiosis is a disease caused by apicomplexan parasites of the Babesia genus. The Babesia microti life cycle involves 2 hosts, which include a rodent, mainly the white-footed mouse (Peromyscus leucopus) and a tick in the Ixodes genus. During a blood meal, a Babesia-infected tick introduces sporozoites into the mouse host. Sporozoites pass into the erythrocytes and undergo asexual reproduction (budding). In the blood, some parasites differentiate into male and female gametes, though these cannot be distinguished by light microscopy. The definitive host is the tick. Once ingested by an proper tick, gametes unite and undergo a sporogonic cycle resulting in sporozoites. Transovarial transmission (aka vertical or hereditary transmission) has been detected for "large" Babesia species but not for the "small" Babesia, such as B. microti. Humans enter the cycle when bitten by the infected ticks. Thus during a blood meal, a Babesia-infected tick introduces sporozoites into the human host. Sporozoites then enter erythrocytes and undergo asexual replication (budding). Multiplication of the blood-stage parasites is responsible for the clinical manifestations of the disease. Humans typically are dead-end hosts. However, human-to-human transmission is well acknowledged to occur via contaminated blood transfusions.

Major pollen allergen Bet v 1-A (Bet v 1.0101) causes an allergic reaction in humans. Bet v 1.0101 is a cause of type I allergic reactions in Europe, North America and the former Soviet Union states, observed in early spring.

BTLA, also known as B And T Lymphocyte Associated, is an inhibitory molecule which is part of the Ig superfamily. BTLA is a type 1 transmembrane glycoprotein in the CD28 family of T cell costimulatory molecules. BTLA is a 3rd inhibitory receptor on T lymphocytes with resemblances to CTLA-4 & PD-1. Moreover, BTLA is a ligand for TNF (receptor) superfamily, TNFRSF14, and HVEM. BTLA-HVEM complexes negatively regulate T-cell immune responses.

Cluster of Differentiation 244 (CD244/Natural Killer Cell Receptor 2B4) contains 2 Ig-like (immunoglobulin-like) domains. CD244 is a cell surface receptor expressed on natural killer (NK) cells (and some T cells) which mediate non-major histocompatibility complex (MHC) restricted killing. NK-cell and target cells interaction via the CD244 receptor is believed to modulate NK-cell cytolytic activity. CD244 molecules function in eosinophil adhesion and chemotaxis, and have a role in the pathophysiology of allergic rhinitis (AR).

Vascular endothelial growth factor is an important signaling protein involved in both vasculogenesis and angiogenesis. As its name implies, VEGF activity has been mostly studied on cells of the vascular endothelium, although it does have effects on a number of other cell types (e.g. stimulation monocyte/ macrophagemigration, neurons, cancer cells, kidney epithelial cells ).VEGF mediates increased vascular permeability, induces angiogenesis, vasculogenesis and endothelial cell growth, promotes cell migration, and inhibits apoptosis. In vitro, VEGF has been shown to stimulate endothelial cell mitogenesisand cell migration. VEGF is also a vasodilator and increases microvascular permeability and was originally referred to as vascular permeability factor.
Elevated levels of this protein are linked to POEMS syndrome, also known as Crow-Fukase syndrome. Mutations in this gene have been associated with proliferative and nonproliferative diabetic retinopathy.

SARS Associated Coronavirus Spike is a causative agent of SARS virus. Diseases caused by Coronaviruses are usually controlled by CD8 T cells. The spike antigen is one of the main surface proteins on Coronavirus, therefore one of the main proteins that are candidates for vaccines.

BCL2L2 promotes cell survival. BCL2L2 mediates survival of postmitotic Sertoli cells by suppressing death-promoting activity of BAX. BCL2L2 is part of the BCL-2 protein family which form hetero- or homodimers and play an important role as anti and proapoptotic regulators. BCL2L2 causes reduced cell apoptosis under cytotoxic conditions. BCL2L2 is involved in the survival of NGF- and BDNF-dependent neurons. BCL2L2 plays an important role in adult spermatogenesis.

Defensins (alpha & beta) are cationic peptides with a wide spectrum of antimicrobial activity which include a significant arm of the innate immune system. There are 6 human beta-defensins, BD-1, BD-2, BD-3, BD-4, BD-5 and BD-6 which are expressed on some leukocytes and at epithelial surfaces. In addition to their direct antimicrobial activities, beta-defensins can act as chemoattractants towards immature dendritic cells and memory T cells. Beta-defensins contain a 6-cysteine motif which forms 3 intra-molecular disulfide bonds.

SURA is a PPIase enzyme and chaperone of Escherichia coli and other Gram-negative bacteria. SURA is a key player in the biogenesis of beta-barrel outer membrane proteins and is involved in cell envelope homeostasis and cell envelope functions. SURA is necessary for the survival of E.coli in stationary phase and needed for pilus biogenesis.

HCV is a small 50nm, enveloped, single-stranded, positive sense RNA virus 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).