THE SECRETORY PROTEIN SEC8 IS REQUIRED FOR PARAXIAL MESODERM FORMATION IN THE MOUSE

The sec8 gene, isolated in a gene trap screen in embryonic stem cells, is required for paraxial mesoderm formation in the mouse. Homozygous sec8 mutant embryos initiate gastrulation but are unable to progress b eyond the primitive streak stage and die shortly afterward. The genomi c locus and cDNA of the sec8 gene have been cloned. An open reading fr ame in the cDNA encodes a 971-amino-acid leucine-rich protein, similar to rat rSec8. A description of the mutant phenotype and the cloning o f the gene is presented here and the results are considered in light o f the possibility that the Sec8 protein is involved in secretion. (C) 1997 Academic Press.