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Major Histocompatibility Complex Class I C (HLA-C) belongs to the HLA class I heavy chain paralogues. The HLA-C (class I molecule) is a heterodimer comprised of a heavy chain and a light chain (beta-2 microglobulin). The heavy chain is anchored in the membrane. Class I molecules have a key role in the immune system by presenting peptides derived from endoplasmic reticulum lumen. Class I molecules are expressed in virtually all cells.

Major Histocompatibility Complex Class II DO Beta (HLA-DOB) is a part of the HLA class II beta chain paralogues. This class II beta chain is a heterodimer which is located in intracellular vesicles and consists of an alpha (DOA) and a beta chain (DOB), both anchored in the membrane. HLA-DOB which interacts with the HLA-DM molecule in B-cells is a significant modulator in the HLA class II restricted antigen presentation pathway. Class II molecules are expressed in antigen presenting cells such as B lymphocytes, dendritic cells and macrophages.

Major Histocompatibility Complex Class I F (HLA-F) belongs to the MHC family which takes part in the presentation of antigens to the T cell receptor. HLA-F is a member of the class I molecules which are expressed in virtually all cells. There are 2 classes of HLA antigens. Class I molecules takes an important part in the immune system by presenting peptides derived from the endoplasmic reticulum.

Major Histocompatibility Complex Class II DO Alpha (HLA-DOA) is a significant modulator in the HLA class II restricted antigen presentation pathway by interaction with the HLA-DM molecule in B-cells. HLA-DOA forms a heterodimer along with HLA-DOB. The heterodimer is located in lysosomes in B cells and regulates HLA-DM-mediated peptide loading on MHC class II molecules. HLA-DOA exhibits very little sequence variation, particularly at the protein level.

Major histocompatibility complex, class II, DR alpha (HLA-DRA) belongs to the MHC class II family. HLA-DRA binds peptides derived from antigens which access the endocytic route of antigen presenting cells (APC) and presents them on the cell surface for identification by the CD4 T-cells. The peptide binding cleft accommodates peptides of 10-30 residues. The peptides presented by MHC class II molecules are generated mainly by degradation of proteins which access the endocytic route, where they are processed by lysosomal proteases and other hydrolases.

HLA-G (Major Histocompatibility Complex Class I G) is a member of the HLA class I heavy chain paralogues. This class I molecule is a heterodimer which comprises a heavy chain as well as a light chain, beta-2 microglobulin, while the heavy chain is fixed in the membrane. HLA-G is expressed on fetal derived placental cells. HLA-G is a non-classical class-I HLA molecule linked with immuno-modulatory & anti-inflammatory properties which interacts with inhibitory receptors such as, ILT2/ILT4/KIR2DL4, that are present on different immune cells. HLA-G inhibits the proliferation of T cells, B cells & natural killer cells, moreover it also induces regulatory T cells.

Major Histocompatibility Complex Class II DR Beta 1 also known as HLA-DRB1 ia a member of the HLA class II beta chain paralogs. Molecule class II is a heterodimer consisting of an alpha (DRA) and a beta chain (DRB), both anchored in the membrane. HLA-DRB1 takes an essential part in the immune system by presenting peptides derived from extracellular proteins. Class II molecules are expressed in antigen presenting cells (APC: B lymphocytes, dendritic cells, macrophages). Furthermore, the beta chain is approximately 26- 28 kDa. It is encoded by 6 exons. While exon one encodes the leader peptide; exons 2 and 3 encode the two extracellular domains; exon 4 encodes the transmembrane domain; and exon 5 encodes the cytoplasmic tail.

Major Histocompatibility Complex Class II DR Beta 1 also known as HLA-DRB1 ia a member of the HLA class II beta chain paralogs. Molecule class II is a heterodimer consisting of an alpha (DRA) and a beta chain (DRB), both anchored in the membrane. HLA-DRB1 takes an essential part in the immune system by presenting peptides derived from extracellular proteins. Class II molecules are expressed in antigen presenting cells (APC: B lymphocytes, dendritic cells, macrophages). Furthermore, the beta chain is approximately 26- 28 kDa. It is encoded by 6 exons. While exon one encodes the leader peptide; exons 2 and 3 encode the two extracellular domains; exon 4 encodes the transmembrane domain; and exon 5 encodes the cytoplasmic tail.

CD74 (HLA class II histocompatibility antigen gamma chain isoform b), is a transmembrane protein (on antigen presenting cells) which is the invariant chain that chaperones MHC class IIdimers from the endoplasmic reticulum to the cell surface. CD74 is expressed by cells of both T lymphocyte and Blymphocyte lineages. CD74 upregulated in several cancers and is also expressed by non immune cells during inflammation. Diseases related with CD74 include thymic epithelial neoplasm and gastroduodenitis. Among its related super-pathways are Immune System and Immune response Antigen presentation by MHC class II. In addition CD74 functions as cell surface receptor for the cytokine MIF.

BAT1 belongs to the DEAD box family of RNA-dependent ATPases that mediate ATP hydrolysis during pre-mRNA splicing. UAP56 protein is a vital splicing factor which is needed for connecting U2 small nuclear ribonucleoprotein with pre-mRNA, as well as takes a key part in mRNA export from the nucleus to the cytoplasm. Mutations in this protein may be connected to rheumatoid arthritis.

MICA (MHC class I chain-related gene A) is a transmembrane glycoprotein that functions as a ligand for human NKG2D. A closely related protein, MICB, shares 85% amino acid identity with MICA. These proteins are distantly related to the MHC class I proteins. They possess three extracellular Ig-like domains, but they have no capacity to bind peptide or interact with ?2-microglobulin. The genes encoding these proteins are found within the Major Histocompatibility Complex on human chromosome 6. The MICA locus is highly polymorphic with more than 50 recognized human alleles. MICA is absent from most cells but is frequently expressed in epithelial tumors and can be induced by bacterial and viral infections. MICA is a ligand for human NKG2D, an activating receptor expressed on NK cells, NKT cells, gamma delta T cells, and CD8+ beta T cells. Recognition of MICA by NKG2D results in the activation of cytolytic activity and/or cytokine production by these effector cells. MICA recognition is involved in tumor surveillance, viral infections, and autoimmune diseases.

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.

MICA (MHC class I chain-related gene A) is a transmembrane glycoprotein that functions as a ligand for human NKG2D. A closely related protein, MICB, shares 85% amino acid identity with MICA. These proteins are distantly related to the MHC class I proteins. They possess three extracellular Ig-like domains, but they have no capacity to bind peptide or interact with ?2-microglobulin. The genes encoding these proteins are found within the Major Histocompatibility Complex on human chromosome 6. The MICA locus is highly polymorphic with more than 50 recognized human alleles. MICA is absent from most cells but is frequently expressed in epithelial tumors and can be induced by bacterial and viral infections. MICA is a ligand for human NKG2D, an activating receptor expressed on NK cells, NKT cells,gammadelta T cells, and CD8+beta T cells. Recognition of MICA by NKG2D results in the activation of cytolytic activity and/or cytokine production by these effector cells. MICA recognition is involved in tumor surveillance, viral infections, and autoimmune diseases.

Killer-cell immunoglobulin-like receptors (KIRs), are a family of cell surface glycoproteins found on Natural Killer (NK) Cells, which are important cells of the immune system. They control the killing function of these cells by interacting with MHC class I molecules, which are expressed on all cell types. This interaction allows them to identify virally infected cells or tumor cells that have a distinctive low level of Class I MHC on their surface. The majority of KIRs are inhibitory, which means that their recognition of MHC suppresses the cytotoxic activity of their NK cell. Only a limited number of KIRs have the capacity to activate cells.
The KIR genes are found in a cluster on chromosome 19q13.4 within the 1 Mb leukocyte receptor complex (LRC). KIR molecules are extremely polymorphic, meaning their gene sequences differ significantly between individuals, so that different individuals have different arrays/repertoires of KIR genes.
The KIR proteins are categorized by the number of extracellular immunoglobulin domains (2D or 3D) and by whether they have a long (L) or short (S) cytoplasmic domain. KIR proteins with the long cytoplasmic domain transduce inhibitory signals upon ligand binding via an immune tyrosine-based inhibitory motif (ITIM). Whereas KIR proteins with the short cytoplasmic domain lack the ITIM motif and instead associate with the TYRO protein tyrosine kinase binding protein to transduce activating signals.
The three Ig-domain from of inhibitory killer cell Ig-like receptor 1(KIR3DL1, NKB1, nkat3, p70KIR) is a NK cell receptor for polymorphic HLA-B determinant. KIR3DLl recognizes the Bw4 determinant defined by sequence motifs at positions 77-83 of the HLA-B heavy chain. The cytoplasmic tail of KIR, which contains two immunoreceptor tyrosine-based inhibition motifs (ITIMs), mediates inhibitory signal transduction that prevents killer cell-mediated cytotoxicity. A His-tag fusion protein of KIR3DL1 cytoplasmic tail (361-444aa) was overexpressed as insoluble protein aggregates (inclusion bodies).

CTLA-4 is a member of the immunoglobulin superfamily and encodes a protein which transmits an inhibitory signal to T cells. The protein contains a V domain, a transmembrane domain, and a cytoplasmic tail. Alternate transcriptional splice variants, encoding different isoforms, have been characterized. The membrane-bound isoform functions as a homodimer interconnected by a disulfide bond, while the soluble isoform functions as a monomer. Mutations in this gene have been associated with insulin-dependent diabetes mellitus, Graves disease, Hashimoto thyroiditis, celiac disease, systemic lupus erythematosus, thyroid-associated orbitopathy, and other autoimmune diseases.

HBsAg is the surface antigenof the Hepatitis-B-Virus (HBV). The capsidof a virus has different surface proteins from the rest of the virus. The antigen is a protein that binds specifically on one of these surface proteins. It is commonly referred to as the Australian Antigen.

SET is part of a complex localized to the endoplasmic reticulum however is found in the nucleus. SET inhibits apoptosis following attack by cytotoxic T lymphocytes and can also enhance DNA replication of the adenovirus genome. SET inhibits acetylation of nucleosomes, particularly histone H4, by histone acetylases (HAT). This inhibition is accomplished by masking histone lysines from being acetylated.

Listeriolysin O (aka LLO) is a hemolysin produced by Listeria monocytogenes bacteria, the pathogen responsible for causing listeriosis. The toxin may be regarded as a virulence factor, since it is crucial for the virulence of L. monocytogenes. LLO is a single polypeptide protein encoded by the hlyA gene and composed of 529 residues. LLO is a thiol-activated cholesterol-dependent pore forming toxin protein; therefore, it is activated by reducing agents and inhibited by oxidizing agents. Still, LLO differs from other thiol-activated toxins, as its cytolytic activity is maximized at a pH of 5.5. Inside the acidic phagosomes (average pH ~ 5.9) of cells that have phagocytosed L. monocytogenes, LLO is selectively activated by maximizing activity at a pH of 5.5. Following the phagosome lysis by LLO, the bacterium breaks out into the cytosol, where it is able to grow intracellularly, and the toxin has reduced activity in the more basic cytosol. Thus, LLO permits L. monocytogenes to break out from the phagosomes into the cytosol without harming the plasma membrane of the infected cell, which allows the bacteria to live intracellularly, where they are sheltered from extracellular immune system factors such as the complement system and antibodies. LLO also brings about dephosphorylation of histone H3 and deacetylation of histone H4 in the early phases of infection, before entry of L. monocytogenes into the host cell. The pore-forming activity is not implicated in causing the histone modifications. The modifications of the histones affect the down regulation of genes encoding proteins involved in the inflammatory response. Therefore, LLO may be significant in subverting the host immune response to L. monocytogenes. At its NH2-terminus it possesses a 25 residues long typical signal sequence excited during the secretion process. Moreover, in its NH2-terminus there is also a 19 amino acids PEST- like sequence that may target this toxin for degradation. The PEST-like sequence found in LLO and is considered crucial for virulence, given that mutants lacking the sequence lysed the host cell. Nevertheless, contrary to PEST's supposed role in protein degradation, evidence implies that the PEST-like sequence may control LLO production in the cytosol rather than increase degradation of LLO.

HBA2 is a member of the globin family. HBA2 takes part in oxygen transport from the lung to the different peripheral tissues. The coding sequences of HBA2 and HBA1 are equal but have a small difference over the 5' untranslated regions and the introns, and a large difference over the 3' untranslated regions. HbA is constituted from two alpha chains and two beta chains which in standard adult life hold about 97% of the total hemoglobin; alpha chains associate with delta chains to create HbA-2 that with HbF (fetal hemoglobin) form the remaining 3% of adult hemoglobin. Alpha thalassemia is caused by removal of each of the alpha genes or removal of both HBA2 and HBA1; nondeletion alpha thalassemias has also been reported.

Hemochromatosis (HFE) is a member of the MHC class I family. The Hemochromatosis protein contains 1 Ig-like C1-type (immunoglobulin-like) domain. HFE is a membrane protein, which is similar to MHC class I-type proteins and associates with beta-2 microglobulin (beta2M). It is assumed that the HFE protein acts to regulate iron absorption by regulating the interaction of the transferrin receptor (TFR) with transferrin. HFE binds to transferrin receptor (TFR) and reduces its affinity for iron-loaded transferrin.

IL-1 alpha is produced by activated macrophages, stimulates thymocyte proliferation by inducing il-2 release, b-cell maturation and proliferation, and fibroblast growth factor activity. IL1A proteins are involved in the inflammatory response, being identified as endogenous pyrogens, and are reported to stimulate the release of prostaglandin and collagenase from synovial cells.

CD74 (HLA class II histocompatibility antigen gamma chain isoform b), is a transmembrane protein (on antigen presenting cells) which is the invariant chain that chaperones MHC class IIdimers from the endoplasmic reticulum to the cell surface. CD74 is expressed by cells of both T lymphocyte and Blymphocyte lineages. CD74 upregulated in several cancers and is also expressed by non immune cells during inflammation. Diseases related with CD74 include thymic epithelial neoplasm and gastroduodenitis. Among its related super-pathways are Immune System and Immune response Antigen presentation by MHC class II. In addition CD74 functions as cell surface receptor for the cytokine MIF.

CD4, a single chain transmembrane glycoprotein, is found on a T cell subset (helper/inducer) representing 45% of peripheral blood lymphocytes. It is also present on 80% of thymocytes and at a lower level on monocytes. It is involved in recognition of antigen presented along with MHC class II by APCs. It serves as receptor for HIV. Antibody to CD4 recognizes T-helper cells required for recognition of class II antigens. It reacts with ~60% of peripheral blood E rosette-positive (E+) cells while showing negligible reactivity with E- cells, monocytes, granulocytes, EBV-transformed B cell lines, and mouse splenocytes.