Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to eukaryotic cells. Microtubules can be as long as 50 micrometres, as wide as 23 to 27 nm and have an inner diameter between 11 and 15 nm. They are formed by the polymerization of a dimer of two globular proteins, alpha and beta tubulin into protofilaments that can then associate laterally to form a hollow tube, the microtubule. The most common form of a microtubule consists of 13 protofilaments in the tubular arrangement.
In biochemistry, dephosphorylation is the removal of a phosphate (PO43−) group from an organic compound by hydrolysis. It is a reversible post-translational modification. Dephosphorylation and its counterpart, phosphorylation, activate and deactivate enzymes by detaching or attaching phosphoric esters and anhydrides. A notable occurrence of dephosphorylation is the conversion of ATP to ADP and inorganic phosphate.
The tau proteins are a group of six highly soluble protein isoforms produced by alternative splicing from the gene MAPT. They have roles primarily in maintaining the stability of microtubules in axons and are abundant in the neurons of the central nervous system (CNS), where the cerebral cortex has the highest abundance. They are less common elsewhere but are also expressed at very low levels in CNS astrocytes and oligodendrocytes.
The Casein kinase 1 family of protein kinases are serine/threonine-selective enzymes that function as regulators of signal transduction pathways in most eukaryotic cell types. CK1 isoforms are involved in Wnt signaling, circadian rhythms, nucleo-cytoplasmic shuttling of transcription factors, DNA repair, and DNA transcription.
Serine/threonine-protein kinase PLK1, also known as polo-like kinase 1 (PLK-1) or serine/threonine-protein kinase 13 (STPK13), is an enzyme that in humans is encoded by the PLK1 gene.
Calcium/calmodulin-dependent protein kinase type II subunit alpha (CAMKIIα), a.k.a.Ca2+/calmodulin-dependent protein kinase II alpha, is one subunit of CamKII, a protein kinase (i.e., an enzyme which phosphorylates proteins) that in humans is encoded by the CAMK2A gene.
Serine/threonine-protein phosphatase 2A catalytic subunit alpha isoform is an enzyme that is encoded by the PPP2CA gene.
Microtubule-associated protein 4 is a protein that in humans is encoded by the MAP4 gene.
Tubulin alpha-4A chain is a protein that in humans is encoded by the TUBA4A gene.
Vasodilator-stimulated phosphoprotein is a protein that in humans is encoded by the VASP gene.
Non-histone chromosomal protein HMG-14 is a protein that in humans is encoded by the HMGN1 gene.
Protein phosphatase inhibitor 2 is an enzyme that in humans is encoded by the PPP1R2 gene.
Stathmin-2 is a protein that in humans is encoded by the STMN2 gene.
Protein phosphorylation is a reversible post-translational modification of proteins in which an amino acid residue is phosphorylated by a protein kinase by the addition of a covalently bound phosphate group. Phosphorylation alters the structural conformation of a protein, causing it to become either activated or deactivated, or otherwise modifying its function. Approximately 13000 human proteins have sites that are phosphorylated.
Ensconsin is a protein that in humans is encoded by the MAP7 gene.
Stathmin-3 is a protein that in humans is encoded by the STMN3 gene.
cGMP-dependent protein kinase 1, alpha isozyme is an enzyme that in humans is encoded by the PRKG1 gene.
Catastrophin is a term use to describe proteins that are associated with the disassembly of microtubules. Catastrophins affect microtubule shortening, a process known as microtubule catastrophe.
Centrosomes are the major microtubule organizing centers (MTOC) in mammalian cells. Failure of centrosome regulation can cause mistakes in chromosome segregation and is associated with aneuploidy. A centrosome is composed of two orthogonal cylindrical protein assemblies, called centrioles, which are surrounded by a protein dense amorphous cloud of pericentriolar material (PCM). The PCM is essential for nucleation and organization of microtubules. The centrosome cycle is important to ensure that daughter cells receive a centrosome after cell division. As the cell cycle progresses, the centrosome undergoes a series of morphological and functional changes. Initiation of the centrosome cycle occurs early in the cell cycle in order to have two centrosomes by the time mitosis occurs.
Edwin W. Taylor is an adjunct professor of cell and developmental biology at Northwestern University. He was elected to the National Academy of Sciences in 2001. Taylor received a BA in physics and chemistry from the University of Toronto in 1952; an MSc in physical chemistry from McMaster University in 1955, and a PhD in biophysics from the University of Chicago in 1957. In 2001 Taylor was elected to the National Academy of Scineces in Cellular and Developmental Biology and Biochemistry.
