Journal of Dental Research, Vol 70, 95-98, Copyright © 1991 by International & American Associations for Dental Research Online Journals
Biosynthesis and secretion of rat salivary proteins by Xenopus laevis oocytes
V. Apekin, G. Goldberger, F. G. Oppenheim and M. A. Paz
Laboratory of Human Biochemistry, Children's Hospital Corporation, Boston, Massachusetts.
Xenopus laevis oocytes injected with poly (A+) RNA isolated from rat
parotid and submandibular glands synthesize and secrete salivary proteins.
Amylase was identified in the media of cultured oocytes injected with rat
parotid mRNA by size and immunoprecipitation with anti-human amylase serum.
Secretion of the salivary proteins was detectable in the medium eight h
following the parotid mRNA injection and continued in a time-dependent
fashion for up to 96 h. In contrast to rat parotid slices in culture, which
demonstrate a regulated pathway of secretion highly responsive to the
secretagogue isoproterenol, secretion of salivary proteins by oocytes did
not respond to the stimulation by isoproterenol. Though parotid mRNA is
presumed to contain the templates encoding the regulated pathway of
secretion, reconstitution of this pathway of secretion in oocytes was not
observed in our experiments. Since Xenopus laevis oocytes secrete
constitutively significant amounts of proteins when injected with salivary
gland mRNA, they are a useful biological system for the analysis of
secretion, processing, and function of salivary proteins.
