Developmental changes in the surface properties of chloroplast membranes.

When the surface properties of etioplast and etiochloroplast membranes from dark grown or variously illuminated leaves of Avena sativa L. are examined by counter current distribution in a Dextran: poly(ethylene-glycol) two-phase system the results may be summarized as follows: (i) Etioplast membranes consist of two main classes with respect to upper phase poly(ethylene-glycol) affinity. (ii) Shortly after illumination the proportion of higher affinity membranes increases and the upper phase affinity of this class also increases. (iii) Further illumination reverses this effect producing a single class of membranes with the high affinity for the lower phase characteristic of membranes of the mature chloroplast. (iv) In rapidly greening leaves (6-9 h illumination) and intermediate class is observed which may represent an intermediate stage in biogenesis. The interpretation of these results is discussed in terms of changes in membrane surface reaction and potential.