Molecular weight and subunit stoichiometry of the chloroplast coupling factor 1 from Chlamydomonas reinhardi

The molecular weight of the Chlamydomonas reinhardi coupling factor 1 (CF1) is 4.2 X 10(5) as determined by gel exclusion chromatography and sedimentation equilibrium. In addition, a measured sedimentation coefficient of 12.9 S results in a calculated molecular weight of 3.9 X 10(5). These molecular weight estimates are too high to support an alpha 2 beta 2-type subunit stoichiometry and are suggestive of an alpha 3 beta 3-type enzyme. The subunit stoichiometry of the C. reinhardi CF1 was determined from the distribution of label into the subunits of uniformly labeled CF1. An alpha: beta: gamma: epsilon ration of 2.9:2.9:1:1 was obtained.