It has been found that parotid glands secrete a factor into blood that stimulates dentinal fluid movement, which in turn, prevents the development of dental caries. This factor, designated as parotid hormone, has been isolated from porcine parotid glands and its partial amino acid sequence has been determined. This study was developed to isolate and identify the cDNA sequence for porcine parotid hormone.
A porcine parotid cDNA library was constructed and hybridized with oligo probes designed based on the partial amino acid sequences of the isolated porcine parotid hormone. Over 100 positive clones were isolated and the complete nucleotide sequences were determined for three cDNA clones. The derived amino acid sequences indicate that these three proteins, ranging from 48.5 to 62.3 kDa, are unusually high in proline (51.8- 60.7%). The structural analysis demonstrates that they contain four general domains characteristic to proline-rich proteins: a signal peptide region, a transition region, a proline rich repeat region, and a carboxyl-terminal region. The last 30 amino acids encoded by two of the cDNAs have 100% identity with the isolated parotid hormone sequence, suggesting that the isolated parotid hormone was probably derived from the end of these cDNAs.
Northern analysis of porcine parotid tissue revealed five major mRNA size classes, ranging from 890 bases to 3550 bases, hybridized to the cDNA probe generated from one of the porcine cDNA clones, suggesting the existence of homologous sequences in these mRNAs, or that these transcripts were derived from closely related genes-a multigene family. In situ hybridization and immunohistochemical staining of porcine tissues indicated that the acinar cells of the parotid glands are the primary location for both parotid hormone related mRNAs and the translation products.
The expression of cloned parotid hormone containing cDNAs produced a single protein in the cell-free system and multiple products in transiently transfected COS-7 cells, as recognized by the antibodies made against the isolated parotid hormone, suggesting that post-translational and/or post-secretory modifications may have taken place.
Raymond G. Hall
Kerby C. Oberg
Aladar A. Szalay
Doctor of Philosophy (PhD)
Year Degree Awarded
Date (Title Page)
Library of Congress/MESH Subject Headings
Cloning, Molecular; DNA, Complementary; Parotid Gland; Dental Caries -- prevention and control; Hormones.
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This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.
Zhang, Qian, "Molecular Cloning of the cDNA for Porcine Parotid Hormone" (2000). Loma Linda University Electronic Theses, Dissertations & Projects. 822.
Loma Linda University Electronic Theses and Dissertations
Loma Linda University. Del E. Webb Memorial Library. University Archives