Forisome

Forisomes are moving proteins occurring in the cells of some plants. Their molecules are about 1-3 µm wide and 10-30 µm long. They expand and contract anisotropically in response to changes of electric field, pH, or concentration of Ca²⁺ ions. Unlike most other moving proteins, the change is not dependent on ATP.

In the "Fabaceae" (legume) plants, forisomes function as valves in sieve tubes of the phloem system, by reversibly changing shape between low-volume ordered crystalloid spindles and high-volume disordered spherical conformations. The change from ordered to disordered conformation involves tripling of the protein's volume, loss of birefringence present in the crystalline phase, 120% radial expansion and 30% longitudinal shrinkage.

Forisomes have possible applications in nanotechnology and biomimetic smart materials, eg. as valves in microdevices or in smart composite materials.

External links

* [http://www.ipam.ucla.edu/abstract.aspx?tid=5939 Forisome: A smart plant protein inside a phloem system]
* [http://www.me.wustl.edu/ME/faculty/aqshen/smartsystem.pdf Forisome based biomimetic smart materials]
* [http://www.medgadget.com/archives/2006/12/forisome_protein.html Forisome Protein, a Key to Biomimetic Materials]