Proteomic Analysis of a Fraction with Intact Eyespots of XXXX and Assignment of Protein Methylation.

@entity71516 @entity534 @entity460 @entity2060 @entity71517
Flagellate green algae possess a visual system, the eyespot. In @entity2060 it is situated at the edge of the chloroplast and consists of two carotenoid rich lipid globule layers subtended by thylakoid membranes (TM) that are attached to both chloroplast envelope membranes and a specialized area of the plasma membrane (PM). A former analysis of an eyespot fraction identified 203 proteins. To increase the understanding of eyespot related processes, knowledge of the protein composition of the membranes in its close vicinity is desirable. Here, we present a purification procedure that allows isolation of intact eyespots. This gain in intactness goes, however, hand in hand with an increase of contaminants from other organelles. Proteomic analysis identified 742 proteins. Novel candidates include proteins for eyespot development, retina-related proteins, ion pumps, and membrane-associated proteins, @entity460 sensing proteins as well as kinases, phosphatases and 14-3-3 proteins. Methylation of proteins at Arg or Lys is known as an important posttranslational modification involved in, e.g., signal transduction. Here, we identify several proteins from eyespot fractions that are methylated at @entity534 and/or Lys. Among them is the eyespot specific @entity71516 protein that influences the size and position of the eyespot and @entity71517 , a protein important for its development.
