title: Molecular characterization of glutamic acid/glutamine-rich secretory proteins from rat submandibular glands.
abstract: A family of abundant rat submandibular gland secretory proteins has been identified in glandular extracts and characterized. By amino acid analysis these proteins contain approximately 35% glutamic acid and glutamine plus 14% proline. They have therefore been named "Glx-rich proteins" (GRP). Plasmids containing cDNAs for a GRP have been isolated from a cDNA library prepared from rat submandibular gland poly(A)+RNA. The nucleotide sequence of these cDNAs have been determined. Approximately half of the protein coding sequence is composed of a 23-residue tandem repeat which is repeated five times. The first four repeats are highly conserved at both the nucleotide and amino acid level and consist of the prototype sequence: Asn-Gln-Glu-Pro-Pro-Ala-Thr-Ser-Gly-Ser-Glu-Glu-Glu-Gln-Gln-Gln-Gln-Glu- Pro-Thr-Gln-Ala-Glu. The expression of GRP appears to be specific to the submandibular gland. In vitro assays demonstrate that the GRP have a marked affinity for hydroxyapatite. This suggests that GRP may play a role in the formation of the protective acquired pellicle at the saliva-tooth interface.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004247:DNA / Q000235:genetics; D044622:Dental Pellicle; D005971:Glutamates / Q000032:analysis*; D018698:Glutamic Acid; D005973:Glutamine / Q000032:analysis*; D008297:Male; D010957:Plasmids; D011061:Poly A / Q000378:metabolism; D011392:Proline / Q000032:analysis; D014176:Protein Biosynthesis; D011506:Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger; D051381:Rats; D011919:Rats, Inbred Strains; D012091:Repetitive Sequences, Nucleic Acid; D013363:Submandibular Gland / Q000032:analysis*
chemical_list: D005971:Glutamates; D011506:Proteins; D012333:RNA, Messenger; D005973:Glutamine; D011061:Poly A; D018698:Glutamic Acid; D012313:RNA; D004247:DNA; D011392:Proline