Expression of cloned zein genes. Proteins from individual cell cultures and mature seeds of BSSS53 and BSSS53 (o2) were prepared and subjected to IEF gel electrophoresis (as described in Methods). Shown fromright to left are samples a4 (azs22;4), a10 (azs22;10), a16 (azs22;16), zp22/D87, and zp22/6. Note that proteins azs22;10 and azs22;16 run in the same position in the gel and that proteins from E. coli always show two bands. The lower band corresponds to the actual endosperm protein and the upper band is possibly a denatured form.