Phototropin
Encyclopedia
Phototropins are photoreceptor protein
s (specifically, flavoprotein
s) that mediate phototropism
responses in higher plants. Along with cryptochrome
s and phytochrome
s they allow plants to respond and alter their growth in response to the light environment. Phototropins may also be important for the opening of stomata.
Phototropins are autophosphorylating protein kinases that activate in response to blue light. When blue light hits the phototropin protein
in the cell membrane
, the phototropin protein will unfold and undergo phosphorylation
that can cause a cascade of events inside of the cell
.
Phototropins are part of the phototropic sensory system in plants that causes various environmental responses in plants. Phototropins specifically will cause stems to bend towards light, and stomata to open. Also, phototropins are important in chloroplast
movements inside the cell. They also mediate the first changes in stem elongation in blue light (before cryptochrome
s become active) and phototropin 1 also is required for blue light mediated transcript destabilization of specific mRNAs in the cell.
Photoreceptor protein
Photoreceptors are light-sensitive proteins involved in the sensing and response to light in a variety of organisms. Some examples are rhodopsin in the photoreceptor cells of the vertebrate retina, phytochrome in plants, and bacteriorhodopsin and bacteriophytochromes in some bacteria...
s (specifically, flavoprotein
Flavoprotein
Flavoproteins are proteins that contain a nucleic acid derivative of riboflavin: the flavin adenine dinucleotide or flavin mononucleotide ....
s) that mediate phototropism
Phototropism
Phototropism is directional growth in which the direction of growth is determined by the direction of the light source. In other words, it is the growth and response to a light stimulus. Phototropism is most often observed in plants, but can also occur in other organisms such as fungi...
responses in higher plants. Along with cryptochrome
Cryptochrome
Cryptochromes are a class of blue light-sensitive flavoproteins found in plants and animals. Cryptochromes are involved in the circadian rhythms of plants and animals, and in the sensing of magnetic fields in a number of species...
s and phytochrome
Phytochrome
Phytochrome is a photoreceptor, a pigment that plants use to detect light. It is sensitive to light in the red and far-red region of the visible spectrum. Many flowering plants use it to regulate the time of flowering based on the length of day and night and to set circadian rhythms...
s they allow plants to respond and alter their growth in response to the light environment. Phototropins may also be important for the opening of stomata.
Phototropins are autophosphorylating protein kinases that activate in response to blue light. When blue light hits the phototropin protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
in the cell membrane
Cell membrane
The cell membrane or plasma membrane is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. It basically protects the cell...
, the phototropin protein will unfold and undergo phosphorylation
Phosphorylation
Phosphorylation is the addition of a phosphate group to a protein or other organic molecule. Phosphorylation activates or deactivates many protein enzymes....
that can cause a cascade of events inside of the cell
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
.
Phototropins are part of the phototropic sensory system in plants that causes various environmental responses in plants. Phototropins specifically will cause stems to bend towards light, and stomata to open. Also, phototropins are important in chloroplast
Chloroplast
Chloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.Chloroplasts are green...
movements inside the cell. They also mediate the first changes in stem elongation in blue light (before cryptochrome
Cryptochrome
Cryptochromes are a class of blue light-sensitive flavoproteins found in plants and animals. Cryptochromes are involved in the circadian rhythms of plants and animals, and in the sensing of magnetic fields in a number of species...
s become active) and phototropin 1 also is required for blue light mediated transcript destabilization of specific mRNAs in the cell.