Dynein is a motor protein (also called molecular motor or motor molecule) in cells which converts the chemical energy contained in ATP into the mechanical energy of movement. Dynein transports various cellular cargos by "walking" along cytoskeletal microtubules towards the minus-end of the microtuble, which is usually oriented towards the cell center. Thus, they are called "minus-end directed motors," while kinesins, motor proteins that move toward the microtubules' plus end, are called plus-end directed motors. This is a list of gene families or gene complexes, that is sets of genes which occur across a number of different species which often serve similar biological functions. ... Cells in culture, stained for keratin The cell is the structural and functional unit of all living organisms. ... Adenosine 5-triphosphate (ATP), discovered in 1929 by Karl Lohmann, is a multifunctional nucleotide primarily known in biochemistry as the molecular currency of intracellular energy transfer. ... The cytoskeleton is a cellular scaffolding or skeleton contained, as all other organelles, within the cytoplasm. ... Microtubules are protein structures found within cells, one of the components of the cytoskeleton. ... Kinesins typically consist of two large globular heads that allow attachment to microtubules, a central coiled region, and a region termed light-chain, which connects the kinesin to the intracellular component to be moved. ...

Dyneins can be divided into two groups: cytoplasmic dyneins and axonemal dyneins, which are also called ciliary or flagellar dyneins. Cytoplasm is like jelly-like material that fills cells. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ...

Cytoplasmic dynein has two heavy chains with globular "heads" that "walk" along the microtubule, to which they are bound by the "stalks". Dynactin (not shown) may help attach the light chains to the cargo. Interactions between the "stalks" and the microtubule must repeatedly form and break (see main text for details)

Image File history File links Cytoplasmic_dynein. ... Image File history File links Cytoplasmic_dynein. ...

Function

Axonemal dynein causes sliding of microtubules in the axonemes of cilia and flagella and is found only in cells that have those structures. Cytoplasmic dynein, found in all animal cells and possibly plant cells as well, performs functions necessary for cell survival such as organelle transport and centrosome assembly (Karp, 2005). The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... cross-section of two cilia, showing 9+2 structure A cilium (plural cilia) is a fine projection from a eukaryotic cell that constantly beats in one direction. ... A flagellum (plural, flagella) is a whip-like organelle that many unicellular organisms, and some multicellular ones, use to move about. ... Schematic of typical animal cell, showing subcellular components. ... The centrosome is the main microtubule organizing center (MTOC) of the cell as well as a regulator of cell-cycle progression. ...

Cytoplasmic dynein probably moves processively along the microtubule; that is, one or the other of its stalks is always attached to the microtubule so that the dynein can "walk" a considerable distance along a tubule without detaching.

Cytoplasmic dynein probably helps to position the Golgi complex and other organelles in the cell (Karp, 2005). It also helps transport cargo needed for cell functioning such as vesicles made by the endoplasmic reticulum, endosomes, and lysosomes (Karp, 2005). Dynein is also probably involved in the movement of chromosomes and positioning the mitotic spindles for cell division (Karp, 2005). Dynein carries organelles and microtubule fragments along the axons of neurons in a process called axoplasmic transport (Karp, 2005). It also carries the HIV virus to the nuclei of cells that have been infected. In cell biology, the Golgi apparatus, Golgi body, Golgi complex, or dictyosome is an organelle found in nearly all eukaryotic cells. ... In cell biology, a vesicle is a relatively small and enclosed compartment, separated from the cytosol by at least one lipid bilayer. ... The endoplasmic reticulum (endoplasmic meaning within the cytoplasm, reticulum meaning little net) or ER is an organelle found in all eukaryotic cells that is an interconnected network of tubules, vesicles and cisternae that is responsible for several specialized functions: Protein translation, folding, and transport (e. ... In biology an endosome is a membrane-bound compartment inside cells. ... Organelles. ... Figure 1: Chromosome. ... Micrograph showing condensed chromosomes in blue and the mitotic spindle in green during prometaphase of mitosis The mitotic spindle is a structure of the eukaryotic cytoskeleton involved in mitosis and meiosis. ... An axon, or nerve fiber, is a long slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neurons cell body or soma. ... Drawing by Santiago Ramón y Cajal of cells in the pigeon cerebellum. ... Axoplasmic transport, also called axonal transport, is responsible for movement of mitochondria, lipids, synaptic vesicles, proteins, and other cell parts to and from a neurons cell body through the cytoplasm of its axon, which is called axoplasm. ... Human immunodeficiency virus (commonly known as HIV, and formerly known as HTLV-III and lymphadenopathy-associated virus[1][2]) is a retrovirus that is the cause of the disease known as AIDS (Acquired Immunodeficiency Syndrome), a syndrome where the immune system begins to fail, leading to many life-threatening opportunistic... In cell biology, the nucleus (from Latin nucleus or nuculeus, kernel) is found in all eukaryotic cells and contains the nuclear genes which form most of the cells genetic material. ...

Structure

Each molecule of the dynein motor is a complex protein assembly composed of many smaller polypeptide subunits. Cytoplasmic and axonemal dynein contain some of the same components, but they also contain some unique subunits. Peptides are the family of molecules formed from the linking, in a defined order, of various amino acids. ...

Cytoplasmic dynein

Cytoplasmic dynein, which has a molecular mass of about 1500 kilodaltons (kDa), contains approximately twelve polypeptide subunits: two identical "heavy chains," 520 KDA in mass, which contain the ATPase activity and are thus responsible for generating movement along the microtubule; two 74 kDa intermediate chains which are believed to anchor the dynein to its cargo; four 53-59 kDa intermediate chains and several light chains which are less well-understood. The atomic mass unit (amu), unified atomic mass unit (u), or dalton (Da), is a small unit of mass used to express atomic masses and molecular masses. ... ATPases are a class of enzymes that catalyze the decomposition of adenosine triphosphate (ATP) into adenosine diphosphate (ADP) and a free phosphate ion. ...

The force-generating ATPase activity of each dynein heavy chain is located in its large doughnut-shaped "head", which is related to other AAA proteins, while two projections from the head connect it to other cytoplasmic structures. One projection, the coiled-coil stalk, binds to and "walks" along the surface of the microtubule via a repeated cycle of detachment and reattachment. The other projection, the extended tail (also called "stem"), binds to the intermediate and light chain subunits which attach the dynein to its cargo. The alternating activity of the paired heavy chains in the complete cytoplasmic dynein motor enables a single dynein molecule to transport its cargo by "walking" a considerable distance along a microtubule without becoming completely detached.

In eukaryotes, cytoplasmic dynein must be activated by binding of dynactin, another multisubunit protein that is essential for mitosis. Dynactin may regulate the activity of dynein, and possiblty facilitates the attachment of dynein to its cargo. Kingdoms Animalia - Animals Fungi Plantae - Plants Protista A eukaryote is an organism with a complex cell or cells, in which the genetic material is organized into a membrane-bound nucleus or nuclei. ... Mitosis is the process by which a cell separates its duplicated genome into two identical halves. ...

Axonemal dynein

A cross-section of an axoneme, with axonemal dynein arms

Axonemal dynein come in multiple forms that contain either one, two or three non-identical heavy chains (depending upon the organism and location in the cilium). Each heavy chain has a globular motor domain with a doughnut-shaped structure believed to resemble that of other AAA proteins, a coiled coil "stalk" that binds to the microtubule, and an extended tail (or "stem") that attaches to a neighboring microtubule of the same axoneme. Each dynein molecule thus forms a cross-bridge between two adjacent microtubules of the ciliary axoneme. During the "power stroke", which causes movement, the AAA ATPase motor domain undergoes a conformational change that causes the microtubule-binding stalk to pivot relative to the cargo-binding tail with the result that one microtubule slides relative to the other (Karp, 2005). This sliding produces the bending movement needed for cilia to beat and propel the cell or other particles. Groups of dynein molecules responsible for movement in opposite directions are probably activated and inactivated in a coordinated fashion so that the cilia or flagella can move back and forth. The radial spoke has been proposed as the (or one of the) structures that synchronizes this movement. Image File history File links Axoneme. ... Image File history File links Axoneme. ... This article is about an organelle. ... AAA or AAA+ is an abbreviation for ATPases Associated with various cellular Activities. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... The radial spoke is a multi-unit protein structure found in the axonemes of eukaryotic cilia and flagella. ...

History

The protein responsible for movement of cilia and flagella was first discovered and named dynein in 1963 (Karp, 2005). 20 years later, cytoplasmic dynein, which had been suspected to exist since the discovery of flagellar dynein, was isolated and identified (Karp, 2005).

References

• Karp G. Cell and Molecular Biology: Concepts and Experiments, Fourth ed, pp. 346-358. John Wiley and Sons, Hoboken, NJ. 2005.
• Schroer, Trina A. DYNACTIN Annual Review of Cell and Developmental Biology 2004 20, 759-779 Entrez PubMed 15473859

The Entrez Global Query Cross-Database Search System allows access to databases at the National Center for Biotechnology Information (NCBI) website. ...

External links

• How Cilia and Flagella Work (axonemal dynein)
• Microtubule Based Movement (cytoplasmic dynein)