RAT HOMOLOGS OF YEAST SEC7P

Mutations in the Saccharomyces cerevisiae sec7 locus lead to a pleiotr opic secretory phenotype that is characterized by an accumulation of G olgi cisternae and a loss of secretory granules, This indicates that t he corresponding gene product sec7p is involved in the budding of secr etory granules from the Golgi apparatus, Here we report the primary st ructure of three rat homologues of sec7p, called msec7-1, -2, and -3. The mRNAs of these genes are expressed in all tissues tested. All msec 7s share the same domain structure in which an N-terminal coiled-coil domain is followed by a sec7-homology domain and a pleckstrin-homology domain, On the protein level, msec7s are present in all rat tissues t ested, with highest protein levels in brain and adrenal, In the adult rat brain, they are present in soluble and membrane-associated pools.