Dynein

Dyneins are tiny machines inside our cells called motor proteins. They help move things around inside cells 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 materials from one place to another inside the cell. They also help when a cell splits into two new cells. They 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. This is different from another type of motor protein called kinesin, which walks in the opposite direction. Both types of these tiny machines are important for keeping our cells healthy.

Classification

Dyneins are special helper proteins in our cells. They 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. 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. It does this 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. It helps move important parts inside the cell, like organelles and vesicles. It also helps position the Golgi complex and move things the cell needs to work properly. Dynein helps during cell division by moving chromosomes and positioning structures that separate cells.

Some viruses use dynein to move inside cells. This helps 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. It has twelve main parts, including two large chains that create movement by using energy from a chemical called ATP. These large chains help move things inside cells by sliding along tiny tubes called microtubules.

Axonemal dyneins are found in tiny hair-like structures on cells called cilia and flagella. They help these structures move by sliding microtubules past each other. This 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 found another type called cytoplasmic dynein. People had thought this type might exist since the first discovery.

Chromosome segregation during meiosis

During the first division of meiosis, homologous chromosomes move to opposite sides of the cell. This helps make sure each new cell has the right number of chromosomes. A protein called dynein helps move the chromosomes, even when certain events called chiasmata are not present. This makes sure each new cell gets a normal set of chromosomes.