GFPgpi (green) spreads from the expressing region (right) attached to argosomes.
Eaton/Elsevier
Eaton first observed the structures when she was studying apical–basal sorting of proteins that have glycophosphatidylinositol (gpi) tails. “It was this completely random observation several years ago,” she says. “When we saw this we just dropped working on apical–basal sorting.”
What she saw were clusters of her labeled protein, a fusion of GFP to a gpi tail, in nonexpressing tissue. The signaling molecule wingless was found in a similar pattern, with both molecules forming gradients that drop with increasing distance from the domain of expression (although the gradient is steeper for wingless).
Eaton believes that lipid carriers are responsible because GFP lacks a surface receptor that could concentrate any proteinthat...
