Molecular motors

Molecular motors are enzyme protein devices that move along cytoskeletal filaments and the proteins are run by ATP hydrolysis. The main system of Biological is driven by the factor of intracellular motility. For example, the microtubules and the actin filaments in cells are tracks, and the molecular motors have two parts the tail domain that are carriers of cargo (organelle or protein) and the motor domain, which work along the track causing motion and thus causes movement.

Firstly, molecular motors are generally of 10-8 m sizeand are driven by the Hydrolysis of ATP and have an average speed of 4*10-3 m/hr Molecular Motors consist of different varieties

· Cytoskeletal – Kinesin, Dynein and Myosin motor groups

· DNA Motors - Helicases

· Rotatory motors – Bacterial flagellum, ATPase

The Track is the medium in which the /molecule motor drives on

The track is a polar structure and motors can go only in a unidirectional way

There are 2 types of general tracks in the cytoskeletal system

·  Microtubules – Cylindrical Polymer and made of α and β tubulents.

o Mainly driven motors are Kinesin and Dynein

·  Actin filaments – Helical polymer

o Mainly driven motor is Myosin

The actual motion as shown in the picture 2 follows a chemical cycle.



The Picture 2 is an example of muscle contraction

·  In Step A the molecular motors bind to the actin Track and the ADP is released

· In Step B the ATP comes in and causes a lift in the motor

· In Step C the hydrolysis causes a 10nm displacement

· In Step D the Next myosin head enzyme is places on the actin track

· In step E the inorganic phosphate is released hence creating a rotation and elevation

Method of identification and development

Lots of methods are used to identify the movement – fluorescence imaging is one of the main technique used especially for the identification of mitotic filaments during mitosis

Optical tweezers and magnetic tweezers are also used in the developmental research of molecular motors.

Relevance in Medicine

It is used in medicine mostly by neuroscientist and neurologists

There are also a lot of pragmatic benefits by the study of molecular motors

·  The study helps in identifying defects in molecular motor and pathways which are associated with neurological disorders or birth defects

·  Also Drugs are also produced which either inhibits or enhances the work of molecular proteins in the tracks thus affecting the motility.

In Conclusion molecular motors are still being researched heavily as the main cause of motility are molecular motors and disorders and syndromes are mainly associated with the working of molecular motors hence different drugs are created to enhance the systematic efficiency. Also Scientist are continuously working on better models of the molecular motor proteins to get a more clear picture of the mechanism of these motors.

References

·   Ron Vale: cytoskeletal motor proteins- http://www.ibiology.org/ibioseminars/cell-biology/ron-vale-part-1.html

·  Cytoskeleton and Motor Proteins - http://www.tocris.com/pharmacologicalBrowser.php?ItemId=187904#.VlI0xd-rQza

·  An introduction to molecular motors -http://thegrantlab.org/resources/handout_motors_CSUSM_11.pdf

·  Figure 1 –  Biological science, 2/e, 2005 Pearson Prentice hall, inc

·  Figure 2 – Drs. T. Purcell and J. Spudich.