Rat homologues of yeast sec7p.

Mutations in the Saccharomyces cerevisiae sec7 locus lead to a pleiotropic secretory phenotype that is characterized by an accumulation of Golgi cisternae and a loss of secretory granules. This indicates that the corresponding gene product sec7p is involved in the budding of secretory granules from the Golgi apparatus. Here we report the primary structure of three rat homologues of sec7p, called msec7-1, -2, and -3. The mRNAs of these genes are expressed in all tissues tested. All msec7s 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 tested, with highest protein levels in brain and adrenal. In the adult rat brain, they are present in soluble and membrane-associated pools.