Primary cilia relation with HH pathway

In 1993 the intra-flagella transport system IFT in the PI was observed and connected to polycystic kidney disease. It was observed that the microtubule structure, called axoneme, grows from the base of the PI, called the basal body. When the cilium is being built, vesicles transport protein pieces to the growing cilium from the base.

Recently, the complexity of the transport system has been described. A special protein attaches and drags proteins through the sea of phospholipids in the membrane, and pulls them into the PI. In this way the primary cilium becomes the communication hub of the cell. Already a number of critical signaling cascades have been shown to live in the primary cilium. This includes the critical hedgehog and retinal signaling pathways.

The transport system uses motors that travel along microtubules to get the important material to the tip of the PI from the base. Special motors are built at the base of the PI and they pull many different types of material into the PI—receptor proteins and building blocks for microtubules. Once at the tip of the PI, the motors deposit the cargo. At the tip Kinesian colorthe motor is altered and becomes a different machine to bring signaling material down the PI to the base. At the based messages are created and sent to the nucleus.

Once at the base of the PI, the motor rearranges itself and becomes the train that drives cargo up into the PI. The train that pulls this material to the tip of the PI is made of at least four motors, one type active at a time. These motors are not just motors; they also interact with the membrane to regulate other functions including sensing extracellular situations and influencing decisions during fetal development. These motors are also able to connect through the membrane to objects outside of the cell to stimulate different types of cell movement. In this situation the motor is anchored to a F1.largeparticular spot, but the entire cell moves when the motor is turned on.

This very complex motor system is critical for the elaborate function of the PI by transporting all receptors and signaling materials that are used for the antenna function.

Defects in these motors in the eye can cause blindness. In the cells of the eye, the tip of the PI is very large bulb and houses the sensors that respond to light but still has a narrow area connecting with the large cell body. All of the light signals have to go through this narrow tube and a defect leads to blindness. Proteins used for sensing light are fragile and very active and many are imperfect. The cell is very dependent on the transport system of the PI to continually restock the proteins. Retinitis pigmentosa is one of the many diseases (ciliopathies) related to defects in this transport system.