Differences between predicted and observed sequences in Saccharomyces cerevisiae

We recently studied the protein composition of a Saccharomyces cerevisiae w ine yeast strain (K310) of enological interest. About 2500 spots of 8-250 k Da observed molecular mass were resolved by two-dimensional gel electrophor esis. Experimental molecular masses and isoelectric points were calculated for most of them. Twenty-seven proteins were subjected to Edman microsequen cing. N-terminal sequences of 12/27 proteins were determined, whereas inter nal sequences of 6/27 proteins were obtained following in situ proteolysis. Comparison between the experimental data and those reported in the SWISS-P ROT database revealed some differences between genotypic and phenotypic seq uences. These are indicative of the changes a protein can undergo with resp ect to the primary structure coded by the genomic DNA. Our results highligh t the need to complement genomic analysis with detailed proteomics in order to refine the vast amount of information provided by DNA sequencing and to find an exact correlation between genome and proteome.