Sequential protein analysis from single identified neurons of Aplysia californica. A microelectrophoretic technique involving polyacrylamide gradient gels and isoelectric focusing.

Electrophoresis in polyacrylamide gradient gels and isoelectric focusing in polyacrylamide gels of capillary size are powerful tools for the analysis of molecular weight and charge properties of small protein samples. This is demonstrated using identified neurons from the abdominal ganglion of the sea hare Aplysia californica. Certain cell-specific peptides, which are considered to be neurosecretory, have been shown to be water soluble when ethylene glycol was employed as a mobilizing agent. Although the mode of action of ethylene glycol is not yet understood, this method may be of value for various extraction procedures. The application of a new staining method that is preferential for separations of sodium dodecyl sulfate-proteins yields information about the charge of water-insoluble proteins which has so far been inaccessible. Preliminary results gained by a small, two-dimensional mapping procedure as well as optical density separation patterns of two different nuclear protein fractionation from a single isolated nucleus outline further possibilties of the microgel techniques.