A. Sucrose density gradient profiles of WT and lut2.1 solubilized thylakoids. Thylakoid membranes from WT and lut2.1 plants were solubilized with α-DM and loaded on sucrose gradient; for each gradient, fractions harvested (left) and chlorophyll distribution (% of total Chl loaded) in the gradient along gradients (right) are indicated. Chlorophyll levels of each band were normalized to the Chl content of WT band 5. Data are expressed as mean ± SD, n = 3. B. Gel electrophoresis of sucrose gradient fractions. Tris-Tricine SDS-PAGE analyses of gradient bands from Figure 1A. Main protein components of each fraction are indicated. Figure abbreviations: B, band; Thy, thylakoids; MW, molecular weight marker. C. Trimerization behavior of recombinant LHCII proteins. LHCII were reconstituted in vitro with different xanthophyll species and trimerization of monomeric subunits was allowed by adding PG, a lipid factor essential for trimerization . LHCII containing a mix of xanthophylls (L,V,N) or only lutein (L) produced trimers, while violaxanthin-binding complexes (V) did not produce trimers. See Experimental Procedures for details. FP, free pigments; MON, monomeric subunits; TRIM, trimeric complexes.