Dynein

Dyneins are a special group of tiny machines inside our cells called motor proteins. They help move things around inside cells by using energy from a chemical called ATP. These little machines walk along tiny threads inside cells called microfilaments.

Dyneins have many important jobs. They carry important materials from one place to another inside the cell. They also help during cell division, when a cell splits into two new cells. Another big job is to help move the tiny hair-like parts on some cells, called cilia and flagella, which help cells move or sweep things along.

What makes dyneins special is the direction they move. They always walk towards one end of the microfilaments, which helps them do their work correctly. This is different from another type of motor protein called kinesin, which walks in the opposite direction. Both types of these tiny machines are very important for keeping our cells healthy and working properly.

Classification

Dyneins are special helper proteins in our cells that can be split into two main groups: cytoplasmic dyneins and axonemal dyneins (also called ciliary or flagellar dyneins).

Each group has different parts that work together. Cytoplasmic dyneins include chains like DYNC1H1, DYNC2H1, and others, while axonemal dyneins include chains such as DNAH5, DNAH7, and more. These proteins help move things inside cells and are very important for many cell activities.

Function

Axonemal dynein helps move tiny hair-like structures called cilia and flagella in cells by sliding tiny rods inside them called microtubules. These structures are only found in cells that have cilia or flagella.

Cytoplasmic dynein is found in all animal cells and helps move important parts inside the cell, like organelles and vesicles. It also helps position the Golgi complex and move things needed for the cell to work properly. Dynein plays a role in cell division by helping move chromosomes and position the structures that separate cells.

Some viruses use dynein to move inside cells, helping them copy themselves. They may attach to dynein using special sequences in their genetic material.

Structure

Each molecule of dynein is made up of many smaller parts called polypeptide subunits. There are two main types: cytoplasmic dynein and axonemal dynein. Both have some of the same parts but also have unique ones.

Cytoplasmic dynein is very heavy, weighing about 1.5 megadaltons. It has twelve main parts, including two large chains that create movement by using energy from a chemical called ATP. These large chains have a special shape that helps them move along tiny tubes inside cells, called microtubules. This movement helps carry important materials inside the cell.

Axonemal dyneins are found in the tiny hair-like structures on cells called cilia and flagella. They come in different forms and help these structures move by sliding microtubules past each other. This sliding makes cilia and flagella bend and move, which helps cells move or push things along.

History

Scientists first found and named dynein, the protein that helps move cilia and flagella, in 1963. Twenty years later, they discovered another type called cytoplasmic dynein, which had been suspected since the first discovery.

Chromosome segregation during meiosis

During the first division of meiosis, homologous chromosomes move to opposite sides of the cell. This process is important for creating cells with the right number of chromosomes. Dynein, a special protein, helps move the chromosomes even when certain events called chiasmata are not present. This ensures that each new cell gets a normal set of chromosomes.