ins and outs of the yeast plasma membrane

The last three pieces of research associated with the late Anthony H. Rose, Professor of Microbiology at the University of Bath, are reviewed. The second messenger cyclic AMP was shown to vary up to 70-fold in concentration during the growth of batch cultures of Saccharomyces cerevisiae with different media. It seems to have a role in transducing information on actual levels of extracellular residual carbon source as well as entry into stationary phase. Another second messenger pathway, involving hydrolysis of phosphatidylinositol bisphosphate, was shown not to be glucose-stimulated as previously thought. Inositol trisphosphate kinase activity was detected but both the existence of the complete pathway and its role were unclear. The yeast Kluyveromyces marxianus isolated from cocoa fermentations was shown to produce abundant and almost pure endo-polygalacturonase in a constitutive manner. Some strains of Saccharomyces cerevisiae also secrete this pectinolytic enzyme. All three projects relate to the central role of membranes in regulating transport of either sensory information or molecules in and out of cells, a key focus of his research for thirty years.