- RIM2, MSI1 and PGI1 are located within an 8 kb segment of Saccharomyces cerevisiae chromosome II, which also contains the putative ribosomal gene L21 and a new putative essential gene with a leucine zipper motif. Démolis, N., Mallet, L., Bussereau, F., Jacquet, M. Yeast (1993)