Phospholipid transfer proteins in microorganisms.

Phospholipid transfer activity has been demonstrated in cell lysates of Saccharomyces cerevisiae, Rhodopseudomonas sphaeroides and Bacillus subtilis, and proteins facilitating phospholipid transfer from the first two organisms have recently been purified. The phospholipid transfer protein from S. cerevisiae has mol. wt. 35 000 with a specificity of transfer for phosphatidylinositol and phosphatidylcholine. The purified phospholipid transfer protein from R. sphaeroides has mol. wt. 27 000 and, although it has the ability to transfer all phospholipid species tested it displays a preference for phosphatidylglycerol. The cellular levels of phospholipid transfer activity in both S. cerevisiae and R. sphaeroides are not strictly related to the level of subcellular membranes. However, in photosynthetically grown R. sphaeroides, the distribution of the activities between soluble and membrane-associated forms is correlated with the level of intracytoplasmic membrane (a postulated membrane substrate).