Recent studies have demonstrated the existence of glycosyl-phosphatidylinos
itol (GPI)-anchored proteins in higher plants. In this study we tested whet
her GPI-addition signals from diverse evolutionary sources would function t
o link a GPI-anchor to a reporter protein in plant cells. Tobacco protoplas
ts were transiently transfected with a truncated form of the Clostridium th
ermocellum endoglucanase E reporter gene (celE') fused with a tobacco secre
tion signal (PR-1a) at the N-terminus and either a yeast (GAS1), mammalian
(Thy-1) or putative plant (LeAGP-1) GPI-anchor addition signal at the C-ter
minus. The yeast and plant C-terminal signals were found to be capable of d
irecting the addition of a GPI-anchor to the endoglucanase protein (EGE') a
s shown by the sensitivity of the lipid component of GPI to phosphatidylino
sitol-specific phospholipase C (PI-PLC) digestion. In contrast, the mammali
an signal was poorly processed for anchor addition. When EGE' was fused to
a truncated form of the LeAGP-1 signal (missing three amino acids predicted
to be critical to signal cleavage and anchor addition), a GPI-anchor was n
ot linked to the EGE' protein indicating the necessity for the missing amin
o acids. Our results show the conservation of the properties of GPI-signals
in plant cells and that there may be some similar preferences in GPI-addit
ion signal sequences for yeast and plant cells.