Formation of purinosomes. A gene construct encoding a fusion protein consisting of formylglycinamidine synthase and GFP was transfected into and expressed in Hela cells, a human cell line. (A) In the presence of purines (the absence of purine synthesis), the GFP was seen as a diffuse stain throughout the cytoplasm. (B) When the cells were shifted to a purine-
[S. An, R. Kumar, E. D. Sheets, and S. J. Benkovic. Science 320:103–