Genetic polymorphism of CON 1 and CON 2 salivary proteins detected by immunologic and concanavalin A reactions on nitrocellulose with linkage of CON 1 and CON 2 genes to the SPC (salivary protein gene complex).

Two new genetic protein polymorphisms (CON 1 and CON 2) were identified in parotid saliva. Genetic polymorphisms of salivary CON 1 (concanavalin A) and CON 2 proteins are determined by autosomal inheritance of one expressed (dominant) and one unexpressed (recessive) allele for each gene. Autosomal inheritance is supported by studies in 26 families including 105 children for CON 1 and 23 families including 95 children for CON 2. Gene frequencies determined for randomly collected salivas from 134 whites, 79 Chinese, and 74 blacks are as follows: for whites, CON 1+ = 0.396 and CON 1- = 0.604, CON 2+ = 0.034 and CON 2- = 0.966; for Chinese, CON 1+ = 0.580 and CON 1- = 0.420, CON 2+ = 0 and CON 2- = 1; for blacks, CON 1+ = 0.581 and CON 1- = 0.419, CON 2+ = 0.007 and CON 2- = 0.993. Both CON 1 and CON 2 proteins, transferred from SDS gels to nitrocellulose, react with concanavalin A. The CON 1 and CON 2 proteins react with antisera prepared to proline-rich proteins (PRP), and the CON 1 and CON 2 proteins have isoelectric points greater than pH 8.5. In randomly collected salivas, the CON 1 protein shows a strong association with Ps proteins, and the CON 2 protein shows a strong association with the PmF protein. On the basis of association data, PmS and CON 2 genes may be outside markers in a linear arrangement of the three genes, PmS, PmF, and CON 2. There is strong evidence for linkage of CON 1 and CON 2 to the SPC (salivary protein gene complex), CON 1 to Ps (15 families, lod score at theta = 0 is 6.77), CON 2 to PmF (7 families, lod score at theta = 0 is 5.93), and CON 2 to G1 (5 families, lod score at theta = 0 is 3.91). In addition to immunologic reactions with the CON 1 and CON 2 proteins, antisera to PRP show extensive immunologic reactions with many other salivary proteins when tested by immunoblotting on nitrocellulose. Some of these proteins were previously identified PRP (proline-rich proteins) that are determined by different PRP loci.