Cytoskeleton Proteins

CTNNB1 (Catenin beta-1) is involved in the regulation of cell adhesion. The majority of catenin beta-1 is localized to the cell membrane and is part of E-cadherin/catenin adhesion complexes which are proposed to couple cadherins to the actin cytoskeleton. Defects in catenin beta-1 are associated with colorectal cancer.

TUBB3 (Tubulin beta 3) is a highly conserved protein with a molecular weight of ~50 kD. Tubulin is the major constituent of microtubules. It binds two moles of GTP, one at an exchangeable site on the beta chain and one at a non exchangeable site on the alpha-chain. Microtubules play key roles in chromosome segregation in mitosis, intracellular transport, ciliary and flagellar bending, and structural support of the cytoskeleton. The two main tubulin isoforms, α- and β-tubulin are usually products of separate genes.

MYL3 (Myosin light chain 3, an alkali light chain) is referred as both the ventricular isoform and the slow skeletal muscle isoform. Myosins are a large superfamily of motor proteins that move along actin filaments, while hydrolyzing ATP. Myosin is the major component of thick muscle filaments, and is a long asymmetric molecule containing a globular head and a long tail. The molecule consists of two heavy chains and four light chains. Activation of smooth and cardiac muscle primarily involves pathways which increase calcium and myosin phosphorylation resulting in contraction.

Cytokeratins are proteins of keratin-containing intermediate filaments found in the intracytoplasmic cytoskeleton of epithelial tissue. There are two types of cytokeratins: the acidic type I cytokeratins and the basic or neutral type II cytokeratins. Cytokeratins are usually found in pairs comprising a type I cytokeratin and a type II cytokeratin. Immunohistochemical detection of cytokeratins is of immense value in tumor cell diagnosis and identification.

Cytokeratins are proteins of keratin-containing intermediate filaments found in the intracytoplasmic cytoskeleton of epithelial tissue. Cytokeratins form a complex network extending from the nucleus to the cell membrane. This network is involved in cellular communication and cytoplasmic organization. Defects in cytokeratin-5 are implicated in numerous skin diseases, including pidermolysis bullosa simplex Dowling-Meara type and Dowling-Degos disease.