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Methionine aminopeptidases and designated peptidase M proteins belong to the M24 family of proteins. MAP protein removes the amino-terminal methionine residue from nascent polypeptides. The active site of MAP contains 2 adjacent divalent metal ions connected by a water molecule or hydroxide ion.

MAX protein is part of the basic helix-loop-helix leucine zipper (bHLHZ) family of transcription factors. MAX forms homodimers and heterodimers with Mad, Mxi1 and Myc. Myc is an oncoprotein implicated in cell proliferation, differentiation and apoptosis. The homodimers and heterodimers compete for a common DNA target site (the E box) and rearrangement among these dimer forms offers a complex system of transcriptional regulation. In contrast to Myc, which is exceedingly regulated throughout progression during the cell cycle, Max is very stable and is much more abundant than Myc.

MORC Family CW-Type Zinc Finger 3 (MORC3) localizes to the nuclear matrix. MORC3 takes part in the regulation of the tumor suppressor protein p53. MORC3may indicate on dermatomyositis (DM) as autoantibodies against this protein have been found in patients.

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.

Adiponectin is a recently discovered 244 amino acid protein, the product of the apM1 gene, which is physiologically active and specifically and highly expressed in adipose cells (Adipokine). The protein belongs to the soluble defense collagen super family; it has a collagen-like domain structurally homologous with collagen VIII and X and complement factor C1q-like globular domain. APM-1 forms homotrimers, which are the building blocks for higher order complexes found circulating in serum.

AFP is normally synthesized in the liver, intestinal tract, and yolk sac of the fetus. Antibody to AFP has been shown to be useful in detecting hepatocellular carcinomas (HCC) and germ cell neoplasms, especially yolk sac tumors.

Small nuclear ribonucleoprotein complexes (abbreviated as U-snRNP) are essential for splicing of precursor mRNA molecules. U1-snRNP is the most abundant RNP particle in the nucleus and consists of one small uridylate-rich RNA (U1 RNA) complexed with several proteins: the three 68/70 kDa, A, C polypeptides are unique to the U1-snRNP particle, whereas 7 so-called Sm proteins (B/B', D1, D2, D3, E, F, G) form a core subparticle that is common to all U-snRNP complexes.
Both the U1-specific proteins and the Sm core particle are targets of autoantibodies which classically have been called the RNP and RNP-Sm specificities, respectively. A clean diagnostic distinction of these specificities has been complicated by the biochemical difficulties of producing clean subparticle fractions from native sources. The use of single recombinant proteins as antigenic targets guarantees a much higher sensitivity and specificity and is the only way to determine RNP antibodies sensu stricto without the disturbing influence of Sm antigens; also with single U1 proteins antibodies will be detected which can be missed because of steric hindrance when using the RNP-Sm complex in an assay.
Autoantibodies to U1-snRNP are present in 95% of patients with Mixed Connective Tissue Disease (MCTD) and 30% of patients with SLE. Antibodies against the 68/70 kDa protein are known to have a high clinical significance in MCTD patients. The 68/70 kDa nomenclature of this protein refers to the fact that different splice variants of the protein are found in human cells.

SNRPC is a member of the U1 small nuclear ribonucleoprotein C family. The SNRPC protein component of the U1 small nuclear ribonucleoprotein (snRNP) particle required for the formation of the spliceosome. SNRPC participates in the processing of nuclear precursor messenger RNA splicing. snRNP particles are tackled by autoantibodies frequently produced by patients with connective tissue diseases.

TPI1 is one of the triosephosphate isomerase family. TPI1 catalyzes the isomerization of glyceraldehydes 3-phosphate (G3P) and dihydroxy-acetone phosphate (DHAP) in glycolysis and gluconeogenesis. Mutations in TPI1 causes triosephosphate isomerase deficiency (TPI deficiency). TPI deficiency is an autosomal recessive disorder which is the most severe clinical disorder of glycolysis and is related to neonatal jaundice, chronic hemolytic anemia, progressive neuromuscular dysfunction, cardiomyopathy and increased susceptibility to infection.

TPM1 is a member of the tropomyosin family which consists of a number of extremely conserved, extensively distributed 35-45 kDa actin-binding proteins that are involved in the contractile system of striated and smooth muscles and the cytoskeleton of non-muscle cells. Tropomyosin-1 is composed of 2 alpha-helical chains arranged as a coiled-coil. TPM1 is polymerized end to end alongside the two grooves of actin filaments and provides stability to the filaments. TPM1 binds to actin filaments in muscle and non-muscle cells. TPM1 also functions in association with the troponin complex to regulate the calcium-dependent interaction of actin and myosin during muscle contraction. In non-muscle cells TPM1 is implicated in stabilizing cytoskeleton actin filaments. Smooth muscle contraction is controlled by interaction with caldesmon.
Alternatively spliced transcript variants encoding a range of isoforms have been described in smooth muscle and non-muscle cells. TPM1 Isoform 1 is expressed in adult and fetal skeletal muscle and cardiac tissues, with higher expression levels in the cardiac tissues, whereas Isoform 10 is expressed in adult and fetal cardiac tissues, but not in skeletal muscle.
Mutations in the TPM1 gene are linked to type 3 familial hypertrophic cardiomyopathy.

PSMB5 belongs to the proteasome B-type family that has a 20S core beta subunit in the proteasome. This catalytic subunit is not present in the immunoproteasome and is substituted by catalytic subunit 3i (proteasome beta 8 subunit). A fundamental function of a modified proteasome, the immunoproteasome, is the processing of class I MHC peptides. PSMB5 exhibits an ATP dependent proteolytic activity and is involved in an ATP/ubiquitin dependent non lysosomal proteolytic pathway.

RBP1 is a member of the calycin superfamily and fatty-acid binding protein (FABP) family. RBP1 is the carrier protein which takes part in the transport of retinol (vitamin A alcohol) from the liver storage site to peripheral tissue. Additionally, RBP1 performs as a bridging molecule to recruit histone deacetylases (HDACs) which is a forceful regulator of gene expression. RBP1 is found in almost all the tissues with higher expression in pancreas, adrenal gland and pituitary gland, fetal liver and adult ovary.

TRAF-interacting protein with FHA domain-containing protein A (TIFA) is an adapter protein that mediates the IRAK1 and TRAF6 interaction following IL-1 stimulation, triggering the downstream activation of NF-kappa-B and AP-1 pathways. The TIFA protein stimulates the oligomerization and polyubiquitination of TRAF6, leading to the activation of TAK1 and IKK through a proteasome-independent mechanism.

Midkine (MK) is the product of a retinoic acid responsive gene, MK, and is a member of a family of heparin binding factors. It contains 121 amino acid residues including 10 conserved cysteine residues, all of which appear to be disulphide linked.
Midkine is expressed during embryogenesis, showing an expression pattern that suggests functions in neurogenesis, cell migration, secondary organogenetic induction, and mesoderm-epithelial interaction.
The widespread downregulation of MK in the adult human is reverted in a number of cancers, in which polypeptides are able to act as both transforming growth factors and promoters of angiogenesis.
Midkine (MK), induces chemotaxis of human neutrophils and was found to trigger mobilization of intracellular calcium of these cells.
Midkine induces histamine release from rat peritoneal mast cells with a rapid response in a dose dependent manner.
Midkine is also a potent stimulator of collagen and glycosaminoglycan synthesis.

Acid Phosphatase-6, also known as ACP6 is Hydrolyzes lysophosphatidic acid (LPA) which contains a medium length fatty acid chain to the corresponding monoacylglycerol. ACP6 shows highest activity with lysophosphatidic acid which contains myristate (C14:0), monounsaturated oleate (C18:1) or palmitate (C16:0), and lower activity with C18:0 as well as C6:0 lysophosphatidic acid.

MTHFD2 plays a role as a homodimer which requires magnesium and inorganic phosphate. MTHFD2 has a pseudogene on chromosome 7 and owns 3 different enzymatic activities. Each of the activities catalyzes 1 of 3 sequential reactions in the interconversion of 1-carbon derivatives of tetrahydrofolate, which are substrates for methionine, thymidylate, and de novo purine syntheses.

SNUPN is a nuclear import adaptor protein which is part of the Snurportin family.
SNUPN is Localized to the cytoplasm and nucleus and contains an N-terminal IBB domain and a trimethylguanosine (m3G)-cap binding domain. SNUPN binds specifically the terminal 2,2,7-m3G-cap at the 5'' end of U snRNPs and is involved in transport of U snRNPs into the nucleus through an association with Importin β.

Platelet factor-4 is a 70-amino acid protein that is released from the alpha-granules of activated platelets and binds with high affinity to heparin. Its major physiologic role appears to be neutralization of heparin-like molecules on the endothelial surface of blood vessels, thereby inhibiting local antithrombin III activity and promoting coagulation. As a strong chemoattractant for neutrophils and fibroblasts, PF4 probably has a role in inflammation and wound repair. Oncostatin-A is a member of the CXC chemokine family. Human PF4 is used for the proof of heparin-induced thrombocytopenia. Furthermore it is used as an inhibitor in the angiogenesis during tumor therapy.

PPP1R14A is a phosphorylation-dependent inhibitor of smooth muscle myosin phosphatase. Inhibition of PPP1R14A results to increased myosin phosphorylation and enhances smooth muscle contraction in the absence of increased intracellular Ca(2+) concentration. Myosin phosphatase can reverse MYL (myosin light chain) phosphorylation to induce a state of relaxation. However, during agonist-induced contraction at constant Ca2+ concurrent inhibition of myosin phosphatase leads to increases in MYL phosphorylation and tension. These calcium-independent increases in myosin phosphorylation and tension are termed calcium sensitization.
Human pregnancy is characterized by the increases of PKN1 expression and CPI-17 phosphorylation in the myometrium. PPP1R14A is mapped to chromosome 19q13.13-q13.2.
PPP1R14A binds directly to protein kinase C and casein kinase I.
PPP1R14A siRNA decreased the level of merlin phosphorylation and consequently Ras and ERK activity in human tumor cell lines.
PKC/CPI-17 mediated pathway in histamine, triggeres cytoskeletal rearrangements causing lung microvascular barrier compromise.

Thymidine phosphorylase precursor (TYMP) is a platelet-derived endothelial cell growth factor that catalyzes the formation of thymine and 2-deoxy-D-ribose-1-phosphate from thymidine and orthophosphate. TYMP is an angiogenic inducer that potently stimulates the growth of endothelial cells and induces chemotaxis. TYMP has a highly restricted target cell specificity acting only on endothelial cells. An increased expression of TYMP is found in a broad array of different solid tumors and inflammatory diseases and is frequently associated with poor prognosis. Mutations in the TYMP gene are linked to mitochondrial neurogastrointestinal encephalomyopathy.

Glycoprotein-9 (GP9) is a small membrane glycoprotein found on the surface of human platelets. GP9 forms a one to one noncovalent complex with glycoprotein Ib, a platelet surface membrane glycoprotein complex which functions as a receptor for von Willebrand factor. The complete receptor complex includes noncovalent association of the alpha and beta subunits with the protein and platelet glycoprotein V. GP9 gene defects cause the Bernard-Soulier syndrome, aka giant platelet disease whose patients have unusually large platelets and have a clinical bleeding tendency.

GREM1 belongs to the BMP (bone morphogenic protein) antagonist family. Like BMPs, BMP antagonists comprise cystine knots and usually form homo- and heterodimers. The CAN (cerberus and dan) subfamily of BMP antagonists, to which GREM1 belongs, is characterized by a C-terminal cystine knot with an eight-membered ring. The antagonistic effect of the secreted glycosylated protein is because of its direct binding to BMP proteins. As an antagonist of BMP, GREM1 takes a place in regulating organogenesis, body patterning, and tissue differentiation. In mouse, GREM1 has been shown to convey the sonic hedgehog (SHH) signal from the polarizing region to the apical ectodermal ridge during limb bud outgrowth. Alternatively merged transcript variants encoding different isoforms have been found for this gene.

CKMT1A is in charge of the transfer of high energy phosphate from mitochondria to the cytosolic carrier, creatine. CKMT1A is a member of the creatine kinase isoenzyme family and exists as two isoenzymes, sarcomeric MtCK and ubiquitous MtCK, encoded by separate genes. Mitochondrial creatine kinase arises in two different oligomeric forms: dimers and octamers, unlike the exclusively dimeric cytosolic creatine kinase isoenzymes. Numerous malignant cancers with poor prognosis have displayed overexpression of ubiquitous mitochondrial creatine kinase which is linked to high energy turnover and inability to remove cancer cells through apoptosis.