Phototropins are photoreceptor proteins (specifically, flavoproteins) that mediate phototropism responses in higher plants. Along with cryptochromes and phytochromes 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 prot… (More on Phototropin)