PRBI gene variants coding for length and null polymorphisms among human salivary Ps, PmF, PmS, and Pe proline-rich proteins (PRPs).
Six closely linked PRP (proline-rich protein) genes code for salivary PRPs that show frequent length and null polymorphisms. We report assignment of Ps proteins to the PRB1 gene, the derived primary structures of Ps 1 and Ps 2 proteins, and the molecular basis for some null alleles among PRB1-coded PRPs (Ps, PmF, PmS, and Pe). The derived primary structures of Ps 1 and Ps 2 proteins were determined by sequencing exon 3 of the different-length PRB1M (medium) and PRB1L (large) copies from subject C.J. with the Ps 1-2 phenotype. The PRB1L copy (coding for Ps 2) contained three additional tandem repeats within the Ps coding region, and the different-length Ps 1 and Ps 2 proteins can be explained on this basis. The molecular basis for the Ps 0 and the Pe- phenotypes was determined in another individual (M.V.O., a PRB2/1 fusion-gene heterozygote) with a single PRB1L copy. A premature stop mutation (CGA [Arg]-->TGA [stop]) occurred at residue 61 in the Ps-coding region. The identical mutation was found in the PRB1L and PRB1/2S (small) copies of a second individual (E.A.) with reduced Pe protein and the Ps 0 phenotype. This individual is a PRB1/2 fusion-gene heterozygote (Azen et al. 1992) with probably three mutated PRB1 copies (PRB1L-PRB1L-PRB1/2S). DNA sequences of the postulated crossover region of the PRB1/2S fusion-gene copy supported the postulated crossover. The PmF- and PmS- phenotypes in the three subjects were due to both the stop mutation and the lack of suitable proteolytic cleavage sites in the PRB1-coded precursor proteins.
Azen
E A
EA
Department of Medicine, University of Wisconsin, Madison 53706.
Latreille
P
P
Niece
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RL
D000483:Alleles; D000595:Amino Acid Sequence; D001483:Base Sequence; D004247:DNA; D005091:Exons; D006801:Humans; D008969:Molecular Sequence Data; D010455:Peptides / Q000235:genetics*; D010641:Phenotype; D011110:Polymorphism, Genetic; D055232:Proline-Rich Protein Domains; D012471:Salivary Proteins and Peptides / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid
D010455:Peptides; D012471:Salivary Proteins and Peptides; D004247:DNA