The chloroplast ATP synthetase consist of the subunits α, β, γ, δ, ϵ and proteolipid only

Abstract

The subunit stoichiometry of the ATP synthetase (CF1‐CF0) immunoprecipitated from Triton X‐100 extracts of chloroplast thylakoid membranes was determined to be α3, β3, γ, δ, ϵ (CF1) and I0.3, II0.6–0.9, III4(6) (CF0). Antibodies against the polypeptides α, β, γ, δ, I, II and ϵ combined specifically with the isolated subunits as analysed by the protein blotting method. Applying this technique, antibodies against the CF1 subunits were found to form complexes with the corresponding polypeptides of thylakoids, whereas those against I (M r 20 000) and II (M r 17 000) combined with M r 26 000 and M r 24 500 membrane polypeptides, respectively. The M r 26 000 polypeptide was identified as the major subunits of the light‐harvesting chlorophyll a/b‐protein (LHCP) complex and the M r 24 500 component seems to be functionally connected with this complex. From the results it is concluded that the chloroplast ATP synthetase consists of the subunit of the α, β, γ, δ, ϵ and III (proteolipid only and that proteolytically altered LHCP polypeptides bind artifically to the protein complex during isolation.

STRUCTURE and FUNCTION OF THE COUPLING‐FACTOR OF PHOTOPHOSPHORYLATION

“…The recent determinations give a molecular weight of 400 kD, instead of 325 kD, for CF, in spinach (Moroney et al, 1983) and Chlamydomonas reinhardii . These results are consistent with a stoichiometry a3 p3 y S E which is in accord with the analyses of uniformly labelled [14C]CF, Suss and Manteuffel, 1983). The subunit 6 is easily lost during CF, purification (Moase and Green, 1981; Fine1 et *To whom correspondence should be addressed al ., 1984) and Berzborn et al (1984) propose that the true stoichiometry is 3 6 per CFI.…”

Isolation, purification and characterization of the ATPase complex from the thermophilic cyanobacterium Synechococcus 6716

“…Although the ; (e) ATPase-rich fraction, diluted-5 x ; (f) protein-rich fraction, diluted 9 x after purification of P3,-on Sepharose 6B; (8) ATPase-rich fraction, not diluted; (h) protein-rich fraction, not diluted F'JATP exchange, the DCCD inhibition and the reconstitution experiments indicate the presence of ATPase complex, in the sodium dodecylsulfate gel electrophoresis we could not precisely identify all the subunits of the complex. In the Iowermolecular-mass region several bands are visible that could be attributed to the F, part of the ATPase complex [25], although a recent report suggests that only one of these bands is an [28]. The clear bands at 28 k D a and 30 k D a are not identified, but are also obvious companions in other ATPase complex preparations [17,27, and are interpreted as integral parts of the FIFO ATPase [16,17,27,29,30,321, as impurities [16,321 or as polymers of low-molecularmass components of the complex [31].…”

“…Although the sodium dodecylsulfate gel electrophoresis we could not precisely identify all the subunits of the complex. In the Iowermolecular-mass region several bands are visible that could be attributed to the F, part of the ATPase complex [25], although a recent report suggests that only one of these bands is an integral part of the F, ATPase [28]. The clear bands at 28 k D a and 30 k D a are not identified, but are also obvious companions in other ATPase complex preparations [17,27, and are interpreted as integral parts of the FIFO ATPase [16,17,27,29,30,321, as impurities [16,321 or as polymers of low-molecularmass components of the complex [31].…”