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Actin is a muscle protein localized in the I band of the myofibrils; acting along with myosin, it is responsible for contraction and relaxation of muscle. Each actin protomer binds one molecule of ATP and has one high affinity site for either calcium or magnesium ions, as well as several low affinity sites. Actin exists as a monomer in low salt concentrations, but filaments form rapidly as salt concentration rises, with the consequent hydrolysis of ATP. It occurs in globular (G-actin) and fibrous (F-actin) forms. Actin is found in all eukaryotic cells (except for nematode sperm). Actin is one of the most highly-conserved proteins, differing by no more than 20% in species as diverse as algae and humans. Its other functions include cell motility, cell division and cytokinesis, vesicle and organelle movement, cell signaling, and the establishment and maintenance of cell junctions and cell shape.

Modulator of apoptosis 1 (MOAP1), is a member of the PNMA family and contains one BH3-like domain and one RASSF1-binding domain. MOAP1 was recognized by its interaction with apoptosis regulator BAX protein. MOAP1 includes a Bcl-2 homology 3 (BH3)-like motif, which is essential for the association with BAX. In addition, once over expressed MOAP1 mediates caspase-dependent apoptosis.

Succinate Dehydrogenase Complex Assembly Factor 2 (SDHAF2) is a mitochondrial protein required for the flavination of a succinate dehydrogenase complex subunit essential for activity of the complex. DHAF2 is necessary for insertion of FAD cofactor into SDHA, the catalytic subunit of succinate dehydrogenase (SDH). SDH is involved in complex II of the mitochondrial electron transport chain and is responsible for transferring electrons from succinate to ubiquinone (coenzyme Q). SDHAF2 gene defects are the cause of hereditary paragangliomas type 2 (PGL2), otherwise known as familial non-chromaffin paragangliomas type 2.

NANOG is a multidomain homeobox transcription factor which functions to maintain the undifferentiated state of pluripotent stem cells. NANOG expression counteracts the differentiation-promoting signals induced by the extrinsic factors LIF, Stat3 and BMP. Once NANOG expression is downregulated, cell differentiation can proceed. Proteins which regulate NANOG expression include transcription factors Oct4, SOX2, FoxD3, and Tcf3 and tumor suppressor p53.

SMAD4 is part of the SMAD family of proteins that mediate signal transduction by the TGF-beta/activin/BMP-2/4 cytokine superfamily from receptor Ser/Thr protein kinases at the cell surface to the nucleus. SMAD4 promotes the binding of the SMAD2/SMAD4/FAST-1 complex to DNA and provides the function of activation required for SMAD1 or SMAD2 to stimulate transcription acts as a tumor suppressor. SMAD4 is a target molecule for functional inactivation in cervical cancer. SMAD4 is an important biomarker for malignant transformation atakes part in inducing apoptosis by modulating Bcl-2/Bax balance.

ATPaseTransporting Beta 2 (ATP1B2) is the non-catalytic component of the active enzyme, which catalyzes the hydrolysis of ATP coupled with the exchange of Na+ and K+ ions across the plasma membrane. The precise function of the beta-2 subunit is not known. The ATP1B2 protein is composed of 3 subunits: alpha (catalytic), beta and gamma.

ATP synthase subunit gamma, mitochondrial isoform L (liver) (ATP5C1) is a member of the ATPase gamma chain family. ATP5C1 catalyzes ATP synthesis by using an electrochemical gradient of protons across the inner membrane throughout oxidative phosphorylation. The catalytic portion of mitochondrial ATP synthase is comprised of 5 different subunits (alpha, beta, gamma, delta, and epsilon) gathered with a stoichiometry of 3 alpha, 3 beta, and a single representative of the other 3.

SNTN is a member of to the S-100 family. SNTN is localized solely to the bridging structure between the cell membrane and peripheral singlet microtubules that specifically exists in the narrowed distal portion of cilia. Exogenously expressed sentan displayed affinity for the membrane protrusions, and a protein-lipid binding assay discovered that sentan bounds to phosphatidylserine which indicate that sentan is the leading molecular component of the ciliary tip to link the cell membrane and peripheral singlet microtubules, making the distal portion of the cilia narrow and stiff to permit better airway approval or ovum transport.

Bestrophin 1 (BEST1) is a part of the bestrophin gene family and is also forms calcium-activated chloride-ion channels in epithelial. This small gene family is characterized by proteins with a highly conserved N-terminus with 4-6 transmembrane domains. BEST1 is extremely permeable to bicarbonate.

Immunity-related GTPase family M protein (IRGM) is essential for clearance of severe protozoan and bacterial infections. IRGM belongs to the p47 immunity-related GTPase family. IRGM serves in innate immune response possibly via regulation of autophagy. IRGM regulates proinflammatory cytokine production and inhibit endotoxemia upon infection and also has a part in macrophages adhesion and motility. Polymorphisms which modify the natural expression of the IRGM gene are associated with a susceptibility to Crohn's disease and tuberculosis.

Latexin enzyme is a carboxypeptidase A inhibitor that is highly expressed in the heart, prostate, ovary, kidney, pancrease, brain and colon. Latexin has no noticeable sequence resemblance with plant and parasite inhibitors, however it is related to a human putative tumor suppressor protein, TIG1. Latexin is down-regulated in the presenilin-1-deficient mouse brain, thus putatively playing a role in Alzheimer's disease.

Thioredoxins are small disulphide-containing redox proteins (within the conserved Cys-Gly-Pro-Cys active site) that have been found in all the kingdoms of living organisms. Thioredoxin contains a single disulfide active site and serves as a general protein disulphide oxidoreductase. Thioredoxins are involved in the first unique step in DNA synthesis. It interacts with a broad range of proteins by a redox mechanism based on reversible oxidation of two cysteine thiol groups to a disulphide, accompanied by the transfer of two electrons and two protons. The net result is the covalent interconversion of a disulphide and a dithiol. It has been suggested that thioredoxin may catalyze the formation of correct disulfides during protein folding because of its ability to act as an efficient oxidoreductant. Trx also provides control over a number of transcription factors affecting cell proliferation and death through a mechanism referred to as redox regulation.

Charged multivesicular body protein 6 (CHMP6) is a member of the SNF7 family. The CHMP6 protein is a core component of the endosomal sorting necessary for transport complex III (ESCRT-III) that is involved in multivesicular bodies (MVBs) formation and sorting of endosomal cargo proteins into MVBs. MVBs contain intraluminal vesicles (ILVs) which are produced by invagination and scission from the limiting membrane of the endosome and generally are transported to lysosomes facilitating degradation of membrane proteins, such as stimulated growth factor receptors, lysosomal enzymes and lipids.

LSM2 is a member of the snRNP Sm proteins family. Sm-like proteins are branded in several organisms based on sequence homology with the Sm protein family. Sm-like proteins hold the Sm sequence motif that is made up of 2 regions separated by a linker of variable length which folds as a loop. The Sm-like proteins are believed to create a steady heteromer present in tri-snRNP particles, which are vital for pre-mRNA splicing. LSM2 binds specifically to the 3'-terminal U-tract of U6 snRNA nad takes part in pre-mRNA splicing.

Charged multivesicular body protein 3 (VPS24/CHMP3) is a member of the vacuolar sorting protein family and function as chromatin modifying proteins. VPS24 links directly with CHMP2 and CHMP4 for the disassembly of ESCRT-III complex in an ATP-dependent manner. During HIV-1 infection, the virus uses the ESCRT-III complex to mediate budding and exocytosis of viral proteins. VPS24 overexpression strongly hinders HIV-1 release.

Regulation Of Nuclear Pre-MRNA Domain Containing 1A (RPRD1A) is upregulated in cells overexpressing cyclin-dependent kinase inhibitor p15(INK4b) and may have a part in cell cycle regulation. RPRD1A interacts with phosphorylated C-terminal heptapeptide repeat domain (CTD) of the largest RNA polymerase II subunit POLR2A, and partakes in dephosphorylation of the CTD. RPRD1A May function as a negative regulator of cyclin-D1 (CCND1) and cyclin-E (CCNE1) in the cell cycle.

Diphthamide biosynthesis protein 2 (DPH2) is a homodimer and each of its monomers can bind a [4Fe-4S] cluster. DPH2 is the target of ADP ribosylating diphtheria toxin (DT) and Pseudomonas exotoxin A (PE). DPH2 was identified by its ability to complement a diphthamide mutant strain, and thus serves in diphthamide biosynthesis. The loss of DPH2 pre-activates NF-kB and death receptor pathways and renders MCF7 cells hypersensitive to tumor necrosis factor.

SLAMF1 is a member of the immunoglobulin gene superfamily and is involved in T-cell stimulation. The SLAMF1 protein is constitutively expressed on peripheral blood memory T cells, T-cell clones, immature thymocytes, and a fraction of B cells, and is swiftly induced on naive T cells after activation. There are probably 2 modes of SLAM signaling: one in which the inhibitor SH2D1A serves as a negative regulator and another in which protein-tyrosine phosphatase 2C (PTPN11)-dependent signal transduction functions.

SNRPE facilitates the cytoplasmic construction of the UsnRNPs by binding to a conserved Sm site on UsnRNA and forming a stable snRNP core complex. While a core protein to UsnRNP, the SNRPE connects with the entire U family of snRNAs including U1–U6. In addition, SNRPE interacts with DDX20 and Small nuclear ribonucleoprotein polypeptide F.

SSR is a glycosylated endoplasmic reticulum (ER) membrane receptor involved in protein translocation across the ER membrane. SSR is formed of 2 subunits, a 34-kD glycoprotein encoded by this gene and a 22-kD glycoprotein. SSR gene creates a number of mRNA species due to complex alternative polyadenylation. SSR is unique since it exploits arrays of polyA signal sequences which are mostly non-canonical.

TFAM is a mitochondrial transcription factor which is a main activator of mitochondrial transcription and is also a participant in mitochondrial genome replication. TFAM is situated primarily in the nuclei of elongated spermatids and takes part in the regulation of gene expression of the haploid male genome. TFAM is linked to mitochondrial disorder in humans characterized by ocular myopathy, exercise intolerance and muscle wasting.

TSR2 is part of the TSR2 family. TSR2 is involved in 20S pre-rRNA processing. Among the diseases which are associated with TSR2 are blepharospasm and diamond-blackfan anemia.

Streptavidin is a tetrameric protein secreted by Streptomyces avidinii which binds firmly to biotin. Streptavidin is wilyde used in molecular biology through its unique high affinity for the vitamin biotin. The dissociation constant (Kd) of the biotin-streptavidin complex is about ~10-15 mol/L. The strong affinity recognition of biotin and biotinylated molecules has made streptavidin one of the most important components in diagnostics and laboratory kits. The streptavidin/biotin system has one of the biggest free energies of association of yet observed for noncovalent binding of a protein and small ligand in aqueous solution (K_assoc = 10**14). The complexes are also extremely stable over a wide range of temperature and pH.