Actins are ubiquitous globular and highly conserved proteins that are involved in various types of cell motility, structure, and integrity. Three main groups of actin isoforms, alpha, beta and gamma have been identified. The alpha actins are found in muscle tissues and are a major constituent of the contractile apparatus. The beta and gamma actins co-exist in most cell types as components of the cytoskeleton, and as mediators of internal cell motility. ACTB is a major constituent of the contractile apparatus and one of the two nonmuscle cytoskeletal actins. Polymerization of globular actin (G-actin) leads to a structural filament (F-actin) in the form of a two-stranded helix. Each actin can bind to 4 others.
β-Arrestin-1 (ARRB1) is a cytoplasmic protein that belongs to the arrestin family. ARRB1 is expressed at high levels in peripheral blood leukocytes and the central nervous system. ARRB1 regulates agonist-mediated G-protein coupled receptor (GPCR) signaling by mediating both receptor desensitization and resensitization processes. ARRB1 acts as a cofactor in the beta-adrenergic receptor kinase (BARK) mediated desensitization of beta-adrenergic receptors. ARRB1 is believed to play a major role in regulating receptor-mediated immune functions. ARRB1 is involved in Toll-like receptor and IL-1 receptor signaling through the interaction with TRAF6.
Beta-casein is a protein that in humans is encoded by the CSN2 gene.Beta-casein is a 226 amino acids protein that belongs to the beta-casein family.It is secreted in milk. Beta-casein palys important role in determination of the surface properties of the casein micelles.
β-Defensin 1 (DEFB1) is a member of the β-defensin family, which is highly expressed by epithelial cells. β-defensins are expressed as the C-terminal portion of precursors and are released by proteolytic cleavage of a signal peptide. β-defensins contain a six-cysteine motif that forms three intra-molecular disulfide bonds. β-defensin 1 is an antimicrobial peptide implicated in the resistance of epithelial surfaces to microbial colonization. Defects in β-Defensin-1 contribute to asthma diagnosis, with apparent gender-specific effects in human. β-defensin 1 may also play a role in the pathogenesis of severe sepsis. In addition, β-defensin 1 is associated with induction profiles in gingival keratinocytes.
β-Defensin 4A is a membrane-active cationic peptide that functions in inflammation and innate immune responses. There are at least 30 β-Defensins, which are distinguished from α-Defensins by the connectivity pattern of their three intermolecular disulfide bonds. Members of the Defensin family are highly similar in protein sequence. This gene encodes Defensin, DEFB4;, which has broad-spectrum antimicrobial activity and may play an important role in innate epithelial defense. They are highly expressed in skin and tonsils, and to a lesser extent in trachea, uterus, kidney, thymus, adenoid, pharynx and tongue. β-Defensin 4A has low expression in salivary gland, bone marrow, colon, stomach, polyp and larynx. No expression in small intestine. The 45 amino acid mature human BD3 shares 38% and 33% amino acid sequence identity with mouse and rat BD3, respectively.
β Galactosidase is a lysosomal β Galactosidase that hydrolyzes the terminal β Galactose from Ganglioside and Keratan sulfate. In lysosome, the mature β Galactosidase protein associates with Cathepsin A and Neuraminidase 1 to form the lysosomal multienzyme complex . An alternative splicing at the RNA level of β Galactosidase results a catalytically inactive β Galactosidase that plays an important role in vascular development. Defects of β-galactosidase (GLB1) are the cause of diseases like GM1-gangliosidosis which is a lysosomal storage disease and Morquio Syndrome B that cause patients to have abnormal elastic fibers. More than 100 mutations have been identified for β Galactosidase, which result in different residual activities of the mutant enzymes and a spectrum of symptoms in the two related diseases.
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