Quantitative immunochemical evidence for identical topography of subunits CF₀II and CF₀I within the photosynthetic ATP‐synthase of spinach chloroplasts

Abstract

Monospecific polyclonal antisera against the 16 kDa and the 18 kDa polypeptides II and I from the CF, moiety of the photosynthetic ATP-synthase in spinach were produced. Inhibition, agglutination and absorption experiments were combined with quantitative determinations in ELISA of residual antibodies and of amounts of CF, and CF,. It follows that subunits CF,II and CF,,I are membrane anchored, extend into the matrix space, and are partially shielded underneath or within CF,. These results on the structure suggest that CF,II and CF,,I are homologous to each other, and in function both homologous to E. coli F,b; thus CF,,II together with CF,I would be part of the 'stalk'.

Rapid purification of membrane extrinsic F1‐domain of chloroplast ATP synthase in monodisperse form suitable for 3D‐crystallization

“…The membrane peripheral domain of the synthase, CF 1 , contains five different types of subunits which are found in a stoichiometry of α 3 β 3 γδε[1]. The membrane integrated CF 0 ‐complex which is composed of subunits I, II, III and IV mediates proton translocation and provides specific sites for the attachment of CF 1 [2–4]. A total of six nucleotide binding sites, three of which are potentially catalytic [5–7] are located on the peripheral F 1 ‐complex.…”