Mr. Custodio et al., EVOLUTION OF CELL-ADHESION SYSTEMS - EVIDENCE FOR ARG-GLY-ASP-MEDIATED ADHESION IN THE PROTOZOAN NEOPARAMOEBA AESTUARINA, The Journal of eukaryotic microbiology, 42(6), 1995, pp. 721-724
Developmental processes in multicellular organisms require structural
elements, such as adhesion molecules, to stabilize cells at functional
positions. In vertebrates, a series of extracellular matrix proteins,
e.g. fibronectin and laminin, are involved in cell adhesion. These pr
oteins contain Arg-Gly-Asp [RGD] at their binding sites. Here we show
that at concentrations above 2 mM the peptide GRGDSPK, comprising the
tripeptide RGD (Arg-Gly-Asp), prevents the adhesiveness of cells of th
e marine amoeba Neoparamoeba aestuarina. In addition, elevated levels
of GRGDSPK cause cells to alter their shapes from those with digitifor
m subpseudopodia to rounded cells with small lobed pseudopodia. These
cells detach from the substratum. These results are specific for the R
GD sequence, because incubation in GRGESPK solution at the same concen
trations had no effect on cell attachment or structure. From these dat
a we suggest that the structural adhesion molecules identified in vert
ebrates show amino acid homologies with those found in unicellular pro
tozoa.