Total number of coding open reading frames in the yeast genome

At the end of 1996 we approximated the total number of protein coding ORFs in the Saccharomyces cerevisiae genome, based on their properties, as 4700- 4800. The number is much smaller than the 5800 which is widely accepted. Ac cording to our calculations, there remain about 200-300 orphans-ORFs withou t known function or homology to already discovered genes, which is only abo ut 5% of the total number of genes. Our results would be questionable if th e analysed set of known genes was not a statistically representative sample of the whole set of protein coding genes in the S. cerevisiae genome. Ther efore, we repeated our estimation using recently updated databases. In the course of the last 18 months, previously unknown functions of about 500 gen es have been found. We have used these to check our method, former results and conclusions. Our previous estimation of the total number of coding ORFs was confirmed. Copyright (C) 1999 John Wiley & Sons, Ltd.