Characterization of the gene encoding the salivary Gln/Glu-rich C-terminal variant A protein.

The rat submandibular gland-specific GRP-Ca gene (encoding C-terminal variant A of the glutamine/glutamic acid-rich protein) has been cloned from a male Wistar/Furth genomic library. The complete sequence, including 2.0 kb of 5' flanking and 0.5 kb of 3' flanking DNA has been determined. Electron microscopic heteroduplex analysis and sequence analysis established that transcripts coding for GRP-Ca and GRP-Cb are encoded by separate genes. The GRP-Ca gene is approx. 4.5 kb in size and is comprised of four exons and three introns. Comparison of this gene with several rodent and human salivary proline-rich protein-encoding genes (PRP) indicates that GRP-Ca shares this exon-intron structure with the rat SMR-2 gene, the hamster H29 gene, and the human PRP genes. In addition, a 28-bp element found in the proximal promoter region of GRP-Ca was found to be highly conserved among the superfamily of PRP genes.