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 beyond the primitive streak stage and die shortly afterward. The genomic locus and cDNA of the sec8 gene have been cloned. An open reading frame in the cDNA encodes a 971-amino-acid leucine-rich protein, similar to rat rSec8. A description of the mutant phenotype and the cloning of the gene is presented here and the results are considered in light of the possibility that the Sec8 protein is involved in secretion.