Forisomes are proteins occurring in the sieve tubes of

Fabaceae Fabaceae () or Leguminosae,International Code of Nomen ...

. 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 An electric field (sometimes called E-field) is a field (physics), physical field that surrounds electrically charged particles such as electrons. In classical electromagnetism, the electric field of a single charge (or group of charges) descri ...

, pH, or concentration of Ca²⁺ ions. Unlike most other moving

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

s, the change is not dependent on ATP. Forisomes function as valves in sieve tubes of the

phloem Phloem (, ) is the living tissue in vascular plants that transports the soluble organic compounds made during photosynthesis and known as ''photosynthates'', in particular the sugar sucrose, to the rest of the plant. This transport process is ...

system, by reversibly changing shape between low-volume ordered

crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...

loid spindles and high-volume disordered spherical conformations. The change from ordered to disordered conformation involves tripling of the protein's volume, loss of

birefringence Birefringence, also called double refraction, is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light. These optically anisotropic materials are described as birefrin ...

present in the crystalline phase, 120% radial expansion and 30% longitudinal shrinkage. In '' Vicia'' it was shown that forisomes are associated to the

endoplasmic reticulum The endoplasmic reticulum (ER) is a part of a transportation system of the eukaryote, eukaryotic cell, and has many other important functions such as protein folding. The word endoplasmic means "within the cytoplasm", and reticulum is Latin for ...

at sieve plates. There are evidences that the forisomes's behavior could depend on Ca²⁺ changes provoked by Ca²⁺-permeable

ion channels Ion channels are pore-forming membrane proteins that allow ions to pass through the channel pore. Their functions include establishing a resting membrane potential, shaping action potentials and other electrical signals by gating the flow of ...

, located on the

and

plasma membrane The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extr ...

of sieve elements. responsible for shape changes. Forisomes have possible applications as biomimetic

smart material Smart materials, also called intelligent or responsive materials, are designed materials that have one or more properties that can be significantly changed in a controlled fashion by external stimuli, such as stress, moisture, electric or magneti ...

s (e.g. valves in microdevices) or smart

composite material A composite or composite material (also composition material) is a material which is produced from two or more constituent materials. These constituent materials have notably dissimilar chemical or physical properties and are merged to create a ...

References

External links

Forisome: A smart plant protein inside a phloem system

Forisome based biomimetic smart materials

Motor proteins Smart materials Plant proteins {{protein-stub