Polypeptide patterns of pea membrane fractions. Comassie Brilliant Blue-stained SDS gels are shown for separated polypeptides from membrane fractions obtained from a 10-step aqueous polymer two phase counter current distribution of pea seedling microsome membranes (1–10; cf. Fig. 1), pea plasma membrane (PM) and pea microsome membranes (MS). The arrows mark the positions of molecular weight markers.