Lj. Swatzell et al., Integrin-like proteins ape localized to plasma membrane fractions, not plastids, in Arabidopsis, PLANT CEL P, 40(2), 1999, pp. 173-183
Integrins are a large family of integral membrane proteins that function in
signal transduction in animal systems. These proteins are conserved in ver
tebrates, invertebrates, and fungi. Evidence from previous research suggest
s that integrin-like proteins may be present in plants as well, and that th
ese proteins may function in signal transduction during gravitropism. In pa
st studies, researchers have used monoclonal and polyclonal antibodies to l
ocalize beta(1) integrin-like proteins in plants. However, there is a dispa
rity between data collected from these studies, especially since molecular
weights obtained from these investigations range from 55-120 kDa for integr
in-like proteins. To date, a complete investigation which employs all three
basic immunolabeling procedures, immunoblotting, immunofluorescence micros
copy, and immunogold labeling, in addition to extensive fractionation and e
xhaustive controls, has been lacking. In this paper, we demonstrate that us
e of a polyclonal antibody against the cytoplasmic domain of avian beta(1)-
integrin can produce potential artifacts in immunolocalization studies. How
ever, these problems can be eliminated through use of starchless mutants or
proper specimen preparation prior to electrophoresis. We also show that th
is antibody, when applied within the described parameters and with careful
controls, identifies a large (100 kDa) integrin-like protein that is locali
zed to plasma membrane fractions in Arabidopsis.