| Calcium-dependent membrane binding proteins constitute an important class of biological effector molecules. Unfortunately, in the absence of suitable in vitro assays the precise intracellular functions of many of these proteins remain to be elucidated. With so many different proteins now being characterized by their relative affinities for both calcium and phospholipid, the need for such specific functional tests has become paramount. One approach that has been particularly fruitful in studying many biological processes has been to employ the combined powers of both molecular biology and genetic analysis in the yeast Saccharomyces cerevisiae. This organism possesses many of the same structural, biochemical and physiological features of higher eukaryotes, making much of what is learned in yeast directly applicable to mammalian cell biology. Using this system significant progress has already been made in understanding and/or clarifying the functional roles of calcium binding proteins such as calmodulin (1,2), Cls4 (3,4), and Kex2 (5). However, as yet no such studies have been performed to test the proposed biological activity of any calcium and phospholipid binding proteins. The work presented here was undertaken to address these issues directly.;Accordingly, the genes for two proteins isolated from S. cerevisiae by calcium-dependent membrane affinity techniques (CAM1 & CAM2) have been cloned and sequenced. The calculated molecular weights of these two species are 47,092Da and 52,076Da, respectively. Disruption of either the CAM1 or CAM2 locus in diploid cells yields four viable meiotic progeny, indicating that neither gene is essential under normal growth conditions. Double disruption mutants are also viable. A search of current protein sequence libraries indicates that the Cam2 protein is unique. The Cam1 protein, however, exhibits over 32% sequence identity (... |
