We describe a procedure allowing extraction of total proteins that performs efficiently with a large variety of plant tissues, based on simultaneous precipitation and denaturation with TCA and 2ME in cold acetone. We also describe protein solubilization prior to IEF, either in classical rod gels or in IPGs, using two different solutions. The procedure is easy to carry out. The major caveats are (1) keep samples at low temperature during extraction, and then (2) manage protein samples at about 22 to 25 degrees C to avoid urea precipitation.